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how to use fragments to create an overlay effect for an add contact function when a button is pressed

I'm trying to create an overlay that is triggered when a button is pressed. This overlay is supposed to allow the user to add their contact and I was wondering how can I use fragments to get this effect like you can see in this mockup.
I am in a dilemna over using fragments is the right choice. My reasoning being that I only need to have it do one task that is adding contacts, and thus I do not need a whole activity.
This is what I have on the main activity right now
I would really appreciate any help on understanding how to make this work.

You can use a DialogFragment.
It behaves like a normal Fragment for the most part. Here is a guide for a basic implementation https://guides.codepath.com/android/using-dialogfragment
They appear automatically in the center of the screen. To get it a bit lower like in your mockup you can change where it is in the window. Here is an answer showing such Position of DialogFragment in Android

Android Development, Google Tutorial

I am following the Google tutorial for building your first android application. I got to the point where I needed to implement the actionbar actions with the functions openSearch() and openSettings().
I implemented all of this in the MainActivity.java file.
My question is this:
In the example app you can type a message and then send it and it displays it in a second activity. In the second activity, the top action bar changes and does not display my Search icon or perform the action when the settings button is clicked. In order to have these icons displayed in the action bar for this activity as well, do I need to add those methods and update onOptionsItemSelected method in DisplayMessageActivity.java as well as in MainActivity.java? Is this the only way to carry the action bar icons/actions over? To retype the same methods in each activity that you want them in? Or is there a better way to do it?
My other somewhat related curiosity is this. The method openSettings() is called when I click the 3 vertical dots and then settings. These 3 vertical dots show up on every activity, and settings is always in the list. However clicking settings obviously doesn't perform the call to openSettings() when in the DisplayMessageActivity and not MainActivity. How is it that settings and the vertical dots are carried over?
Second to last, how can I add other selections to the drop down list from the options/vertical dots in the action bar? Settings is always there although it responds differently in each activity which was my first question. But I would like to add certain things to the options menu that are on all activities, and some things that are unique to some activities. I assume there must be a better way than repeating switch statements and methods in every Activity.java file.
And finally, what is the best practice to implement an action bar over multiple activities?
Obviously different activities will often have different icons/actions in the action bar, however some things like the 3 vertical dots(options) and settings within that would obviously be acceptable to have in every Activity, while it would be nice to add other things to the options list I don't see why settings should ever change across activities. Yet as I stated before the method is not called in DisplayMessageActivity unless I repeat the code in DisplayMessageActivity.java that I had added to MainActivity.java. I'm confused as to where I can add these so that they are displayed on all activities without repeating code. And I'm confused as to how the actionbar's options/vertical dots are carried over to all activities while others require the repeating of code in each activities' java file that I want them to show up in.
I know this was a bit of a long winded quesiton, I will clarify if necessary. I'm just a bit confused. I was able to make it through the tutorial fine as I have a decent understanding of java. However google's guide isn't written that well and the Android environment is very confusing to a beginner.
I do understand how things work to a degree, I just want to ensure that I'm actually doing it in a way that when my app grows in complexity it won't be a mess of unnecessarily repeated statements and methods.
Thanks in advance for any assistance and tips.

In order to have these icons displayed in the action bar for this activity as well, do I need to add those methods and update onOptionsItemSelected method in DisplayMessageActivity.java as well as in MainActivity.java? Is this the only way to carry the action bar icons/actions over? To retype the same methods in each activity that you want them in? Or is there a better way to do it?
That is certainly one solution, but as you obviously know, it's not a very good one. There are at least two alternative solutions:
Create a MenuActivity class which implements all the logic for common menu items and then extend this class from all of your activities, rather than extending the standard Activity class.
Use fragments to implement your UI. Fragments are similar to activities in that they create UI elements from an XML layout. One difference is that they live inside a "host activity". In this particular case, the host activity will provide the common menu functionality and each fragment can customize it further depending on your needs.
How is it that settings and the vertical dots are carried over?
Most likely your DisplayMessageActivity overrides onCreateOptionsMenu() and inflates a menu XML layout which was created by Android Studio (or Eclipse?) when you created the activity class.

add a new button from another fragment class

My problem is that I have two classes that extend Fragment.Now I have a button(its name is save) in 1 fragment class.I want to add a new button in another fragment class when 'save' button is clicked.I know I need to have an onClickListener for the 'save' button but I don't know how to go further from there.I also want an onClickListener for the new created button.
Any help would be much appreciated.

use interface to communicate from one fragment to another.
follow the below link. You will find out something:
onItemClickListener between two fragments

There are a number of ways to do this, depending on the relationships between fragments, whether they are nested etc.
1) Use SharedPreferences. That means you would write to the apps defaultSharedPreferences some flag which says "save has been pressed", and then in the other fragment any time you call createView you would check this flag in preferences. IF save has been pressed you would then show the button.
This approach has a few issues though depending on how long you want to show this button for, if it should be shown forever etc.
2) The interface approach mentioned is valid, but it has coupling issues, and may not be suited to the framework you have in place.
3) Broadcasts - you can use intents and send messages between fragments. This runs into some vaugeness issues (You need to be careful when documenting broadcasts and intents) and can be somewhat opaque to other readers.

Start android program with settings

When my program start I would like to do some settings before is really starting. Forexample choose the user, check the updates and so on. After these settings I would like to start the main program with the appropriate.
Which is the best way to do this?

You can run an AyncTask, or multiple if you need one for each check, in your onCreate() and show a ProgressDialog while the data is being fetched then cancel it in onPostExecute() and move on to the rest of the MainActivity depending on the data that is downloaded. If you need help getting started with AsyncTask you can see this SO answer on the basic structure.
If you use a ProgressDialog then the app will still start but the users will see something and know that data is loading so they won't feel like it is freezing or taking too long to load (or at least they will know why it isn't loaded right away).
AsyncTask Docs
Edit after comment
For what you said you want in your comment you can do this easily with an Activity that has a Dialog Theme. This will give you the functionality you need (a couple Buttons and store the values) but it will look like a little popup. You can't use an actual Dialog as they need an Activity, the same with any menus, AFAIK. Just create your Activity and make it the launcher and main using the Intent-filters then also add the following line to that Activity's tag in the manifest
android:theme="#android:style/Theme.Dialog"
This approach should give you what you need

There are numerous ways to do that.
First - your app is doing some heavy stuff and this may be freezing user interface. In that version do:
1. Create and activity on what you will override onCreate method and set some content with a spinner - so something will be alive and user will see that something is being done.
2. after you will compute all the things that your app need and may I suggest write it to some global variables override onStart method in what change layout to what suit you and give a user a great UI!
Second - you app is not heavy lifting here just throw everything into override of onStart method.
Handy material here for educating:

How to validate input data in a Tab on Tab Change?

I have an app structure like this:
Background: The Parent activity #1 is just holding the tab host, tab widget and is also setting up the 3 tabs to have their content set to the 3 tab activities (tab1, tab2, tab3 activities).
Update: I tried calling my validation method inside
onTabChangedListener in Parent Activity #1 but I got a Null Pointer
Exception. Couldn't really trace it to anywhere. I did
commented/deleted conflicting code but still I am not getting the
bottleneck.StackTrace(PasteBin Link).
Code for Parent Activity #1,Tab#1
Activity
Problem: I want to validate data entered by user in the form field(s) in the individual tab activities onTabChanged event but I am unable to set more than a single setOnTabChangedListener. Am I missing something here? The listener(s) are set in their own tab# activities under oncreate method. Apart from trying the above technique, I had tried setting up the listener in onResume() under the main Parent activity #1. But the on Resume() method was never invoked. I got a null pointer exception too.
Idea behind validation being: I want that while the user is changing tabs, the data should be validated before he can skip over a tab. So, ineffect I would require tab#1 to validate data in a event similar to onTabChanged if tab#2/tab#3 is selected. Also, this would apply if current tab#2 is selected and user selects tab#1/tab#3
Any advice will be appreciated..Thanks for reading..

I want to validate data entered by user in the form field(s) in the
individual tab activities onTabChanged event but I am unable to set
more than a single setOnTabChangedListener.
There is no need for a second OnTabChangeListener and even if you could set it it wouldn't help you. As you constructed the code you need access to the child activities. You can do this by using one of the answers in this question. The problem is, that those answers, except the accepted one, use deprecated methods.
My method, that I proposed in the comments is to have a static boolean field in each of the child activities used as tabs and let all of your activities update that boolean flag whenever there is a change of state of the views in those activities(if you check a CheckBox, enter something in an EditText etc). Then you can simply check the flag for the desired child activity in the OnTabChangeListener. My method should work but your code is a bit messy so you would have to modify it quite a bit.
I had tried setting up the listener in onResume() under the main
Parent activity #1. But the on Resume() method was never invoked. I
got a null pointer exception too.
It's normal that you get a NullPointerException with your code as I haven't seen where you initialize the references to the child activities that you use in the OnTabChangeListener.
Also:
Don't use TabActivity. It's been deprecated in favor of the Fragments framework which is more flexible. Those fragments could help you because, I think you want to stop changing the tabs if the validation of the current page fails and the OnTabChangeListener might come a bit late for that(but I may be mistaken about what you want).
As a side note, use equals in your code to test String equality and not ==.