Open (run) Intervalon.exe. Administrative privileges are not required. The board window appears.
Now you can play (just touch note-key buttons, or press PC keyboard keys), and change settings.
The dotted button is middle C.
In the initial setting, you play middle C-D-E mid-board.
C,C#,C##...,Cb,Cbb,Cbbb.. share the same button color.
Messages are displayed at the bottom of the window.
For example, if you keep pressing two note-keys at the same time (cord), the interval and cents between them are displayed.