Mechanics of playing the instruments does not differ significantly from that of Guitar Hero or Rock Band.
You can play on one of several instruments: drum, flute, guitar, harp and violin. You can buy them from some merchants:
Deser (M32:7), (M32:9), (M32:11), (M32:12), (M32:14)
Remember that you must also purchase music sheets (not all allow you to play melodies on all instruments).
During the game you only operate on four keys: Q, W, E, R. The easiest instrument is the drum, the most difficult are violin and harp. For performance you can earn some auras, but only if people will gather around. The score is multiplied by the number of listeners.