When starting out, first load some music into the empty Replayer app.
Image: Loading tracks or compilations or into Replayer
There are two types of compilation. When you work with an organisation or a choir/band leader, they might provide you with a ready-made compilation with all tracks for your practice or rehearsal already contained. Just load the file and start practising, for example by using the loop modes.
By loading a track, you actually start creating your own compilation.