Q W E R T Y U I O P
^ A S D F G H J K L cr

These keys are for singing / playing music.

 Q  A  W  S  E  D  R  F  T  G  Y  H  U  J  I  K  O  L  P
-9 -8 -7 -6 -5 -4 -3 -2 -1  0  1  2  3  4  5  6  7  8  9
mn3         dom   mj6               mn3         dom   mj6 
   med                    tonic        med                

^ cr  -  shift down/up to next tonic or to the selected note

You have around 3 octave range (1.5 below and 1.5 above the base tonic), can be increased with practise.
Or, could play pan-octave harmonies for simplicity.
The central G key gives the tonic note.
The other 11 notes of the scale are harmonically derived from this.
An upward major scale goes like this for example:

  G H J I O P T G

The voice can continue up or down to the next range if you have gone past the '6th' note.

The keyable notes range from tonic up to major 6th and down to minor 3rd below.
To play a 7th above / 2nd below, play the one next to the tonic instead.
The extra keys ^ and cr are used to shift up and down by an octave.
Also, if you hold ^ or cr and press a note, it will shift up or down to use that note as a new tonic.
The G key will then play that note (normalized on to the equal 2^(1/12) scale).