Android : Trying to understand viewPager

I've been looking through the tutorial app (http://developer.android.com/training/implementing-navigation/lateral.html) at as far as I can tell, each fragment is created through the inflater.inflate commands such as

View rootView = inflater.inflate(R.layout.fragment_section_launchpad, container, false);

But what I don't understand is how it actually switches screens? It seems like in all the demos it has the SAME frament/layout for each screen. So I guess I'm just trying to understand where the code is that determines what screen to switch to so that I can understand how to add multiple fragments to the selection. Any help for a new developer would be greatly appreciated!