So far you have played Am7, Cmaj7, and D7. The three remaining chords are Gmaj7, Bm7 and F#N7. The most important of these three chords - Gmaj7 and Bm7 - are written here.
Note that each scale tone chord extension contains the basic scale tone chords that you learned in Lesson 12 (e.g., the Gmaj7 chord is a G chord with an F# note added). Play all the scale tone extension chords in the key of G as written on the following staff, ascending and descending.