The folder 'MIDI Pieces' contains three sets of MIDI files. Each set of MIDI files is a song:
Space (the final frontier)
Reggae Groove
In Need of Company.
Each song is provided as a complete multi-track MIDI selection, and as single-track MIDI files for each instrument/part used to make the song.
The names of the individual parts should be used as a quick start guide to sound selection, especially when using the rather limited and somewhat wimpy internal sounds on the Mac.
Use of a MIDI interface, along with a MIDI or General MIDI device (or devices) will allow you to hear something much closer to how each song really sounded when they were recorded.