The Sifteo hardware is limited to 8 audio channels. Wildflower has divided those up for 4 music channels and 4 sound effects channels. The upper 4 channels are used for music.
Wildflower does not yet provide a high level interface for playing music. On start up it will play a single track of looping xm music. It is possible that in future updates or by writing your own code to extend the ability to play more tracks of music.
By default music is disabled in the example project because it can slow down the game in some of the more complicated areas. If you'd like your game to start with music that can be toggled via the [Sifteo Game Settings] button on the [Menu Bar] of the editor. Also players can use the pause in game pause menu to toggle music while playing.
You can change which song is loaded by modifying the Music asset in "assets.lua", or simply overwriting the default music xm file in your "source/data/music" folder. Music can slow down your game considerably so keep that in mind if you decide to include music. One option is to have a very simple music, maybe using only 1 or 2 channels to have less of an impact on framerate.
Wildflower comes packaged with two songs for use in your games created by René Weirsma the same composer who wrote the music for Squaresville. They were designed as 4 track songs specifically to work with Wildflower. These tracker files have been released under the same license as Wildflower so feel free to remix them and use them in your games for non-commercial purposes.
For more information about writing music for Sifteo games check out these resources...