Once registered, Apple Music will ask for some information about the kind of music you like. This is to help offer the best recommendations for new music or curated playlists.
Tap the pink bubbles labelled with the music genres you like and double tap genres you really like. Press and hold any you really hate. Then tap Next and repeat the same steps for another set of bubbles, this time filled with names of popular artists rather than genres.
If you ever want to go back and change your selection, tap the Account button in the top left of the Music app and press Choose Artists For You.
The bubbles help to give Apple an initial idea of your preferred music, but you can continue to teach the service by tapping the button to signify that you love a track. The more songs you register your love for, the better Apple Music’s recommendations in the For You tab will become.