When you select new from Trippy's main menu you see this screen.
The key to navigating Trippy is the "A" button and the directional pad. (D-pad)
Almost everything you do requires you to use the D-pad to move between functions. To change functions you hold the "A" button and press left, right, up or down.
For example, to change a note on the note sequence. You press Right on the D-pad and choose the note you want to change. Press and hold "A" and move the note indicator to the key on the keayboard you want to hear. When the beat indicator comes around to the note you selected, you'll hear it play.
Once you've composed the music on this channel, you can switch to the "Sound II" channel or the "Noise" channel by pressing "Select."
Once you have the basic functions down you can figure out most of Trippy's limitations by experimenting with it.