To be able to select a song, tap on the loop browser - symbol at the top right, the loop. The icon of the track browser can be found in the top left. Because in these cases you would first have to create a track using a short recording that you will later delete in order to access the track browser.

In the current garage band version, this is no longer so intuitive with a piano or guitar project. First press the brick symbol in the upper left corner of the screen to select the track view. But you don't have to sing yourself, don't worry. First you create a new project, the easiest way to do this is with the 'Audio Recorder'. To save a song as a ringtone, you must first import it into Garageband.