Shoot to push yourself, and in which direction depends on the weapon :)
There are not many levels in the game, but for that you have a map editor at your disposal, create them and share them with others. (the created levels lie along the path of Android/data/com.FreezyCat.BounceTheBall/files/Maps)
There are two types of weapons in the game: standard (pushes you in the opposite direction) and special (pushes you in the direction of shooting). You can buy weapons in the store.
The interface is pretty simple, so you'll get used to it quickly.