Simple Arduino code for MIDI (ideally need a Bare Conductive Touch Board)

Hi there, I need someone to help me out with some simple Arduino code for a Bare Conductive Touch Board (therefore this work would probably be easier for somebody who owns one, although may well be possible without). I'm working with MIDI through GarageBand at the moment, using the Touch Board as a controller. The basic idea, is that when a user has pressed a certain amount of notes, the notes each pin corresponds to change (making the keyboard difficult to play, sort of like a puzzle) So exactly this: when (random number between 3 and 12) notes have been pressed, the notes each of these pins correspond to are swapped at random. Example: the notes the pins correspond to are A3, B3, C3, D3, E3, F3, G3, A4, B4, C4 User then presses 3-12 keys (in this case, A, B, C) The notes the pins then correspond to are B3, C3, A3, D3, E3, F3, G3, A4, B4, C4 The program then continues like this, waiting for 3-12 notes and then swapping notes around accordingly I just have no idea how to begin solving this, so even a fifteen minute chat about what approach might work best would be hugely appreciated.