Even as I have no idea of writing music, I have been looking at the program to know how it can be used.
There are two lines of icons at the bottom of the screen. When starting the program, the leftmost icon of the upper line is highlighted. We can move with the joystick over the two lines of icons.
The icon with a D on top of a chip is used to select Dave or Midi-Out as the output of the reproduction. Although it can be toggled at any time, better don't do it when playing a song, because notes can be left hanging.
Then, to the right of the upper line, the six player icons follow, and then more to the right, another six icons for Octave, Velocity and Tempo.
The four rightmost icons enter to edit one of four aspects of the program: Notation, Names of the instruments, Load and Save, and ADSR. To exit from that separate screens, the Stop key must be pressed.
While on the Notation, Names and ADSR separate edit screens, the two lines of icons are still accessible by pressing ESC. one more press at ESC return to the Editing cursor.
On some editing screens the bottom icons line can be toggled to other icons with the CTRL key. Then, the line will show other useful icons to configure the program, and even to erase the current song.
The Notation is the most important edit screen of all. Once on it, the shift keys can be used to move by the music sheet. But we also can use INS, SUPR, DEL like on a text editor. A symbol can be selected from the bottom icon line toggling cursors with ESC.
Other keys of the Notation mode are B, L, M, O, R, S and F1-F6, some of them have unknown use for me.