The first thing to know is that GarageBand is only available for Macintosh computers. After you open GarageBand, here are the general steps for using it: 1) create a new project, 2) set the Beats Per Minute, 3) create a new track and arm it for recording, 4) record a live instrument, use one of GarageBand’s software instruments, and/or use Apple’s huge library of loops and sounds. Then repeat this process of each track, combine them together into a song, and hit Share → Export Song to Disk to bounce it to a WAV file.