[android help] How to show second fragment from first fragment with in a single activity

I am developing a simple android app only for tablets and using android 4.0. My application have the main screen like as follow:

Oncreate() of Main Activity I am adding Fragment A in the main.xml using following code:

FragmentTransaction ft = getFragmentManager().beginTransaction();
Fragment imageFragment = new ImageFragment();
ft.replace(R.id.fragment_container, imageFragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(null);
ft.commit();

This fragment A just have only a Image view which is clickable. Now I want that when user click on Image view then another fragment (Fragment B) should call and it replace the image view. The Fragment B have a VideoView which play the video.

So My second screen should be like as follow:

My problem is I am not gettting "How to call second fragment from the first one with in main screen activity?"

I can use different activities but I do not want to do so and just want to run this using fragments.

Please guide me.

.

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