There are no MIDI files to download - the purpose of MIDI is that you create the music using a MIDi keyboard connected to the computer or the computer keyboard to play a selected instrument for the track and record it.
Alternatively you can write the MIDI notes in the MIDI Editor - these are all covered in the manual available under Help
I would suggest you view the Music Maker beginners tutorials by @browj2 in the Tutorial section of the forum.