Sample app for Android Studio - modifying for testing

Hi all
I am very new to any form of mobile app development and took up on using DreamFactory as the back end RESTful service.

I have managed to import the sample app in to Android Studio and have it running successfully linked to my DSP with sample data (add_android / Address Book Android).

Was wondering if anyone could give me clues how to modify that sample app so the page you see once logged in relates to a different back end app / database I have in my DSP.
I can see how to adjust the back end app for referencing on the android app but have no clue how to set up that “second page” (post authentication page) to play around with the system and try to display data I want.
Not sure which part of the app it redirects to / displays once authenticated - as a starting point to try and formulate a page I want with very basic info (will be using GET commands against a MySQL service I have defined and working).

Sorry if that is a bit vague, am very new but keen to get my head around it all looks very promising.

Thanks in advance.