Can you play a single row yet? If so, then all you need to do is get in a comforable chair and work at transitioning from one row to the other, playing chords, AND playing different notes on different rows. With a triple row you can now play minors and sevenths which you could not play with a single row. If you have someone who can show you some chords and single key progressions, great. If not, just experiment, make notes of what you've learned, and practice-practice-practice.