Android Stack OverFlow: Android : Implementing back button in android fragment activity

I'm using this tutorial to implement facebook login etc.

I have added new fragment in this to show list of friends. Now when I press back button on my newly added fragment it takes me to the SPLASH fragment, I want same behaviour on back button on action bar. Means when I'm on my new fragment it shows me a back button on action bar. And pressing that back button takes me back to the SPLASH screen.