You can compose a song using sample chord progression.
I explained how to compose a song using sample songs in the "Practice" already.
How to compose a song using sample chord progression is very similar one.
On the main menu, click Sample.
Click "Chord progression of bar 4" or "Chord progression of bar 8", and then click the chord progression that you want.
On the main menu, click the Compose button, and then Playback button.
If you don't like the song, click the Compose button again.
If you like the part of the melody in this song, click the Fix button that corresponded to the part.
Then the letter "Fix" will appear on the button.
After this even if you click the Compose button, the melody is not changed.
The melody that was fixed can change by using "Select melody" button on the right side.