You will learn far more from Doug's courses than their titles identify. This guy will really motivate you. Finally, someone has made the construction of basic chords understandable by offering the spoken word as an accompaniment to the printed page. Doug makes everything so simple that you wonder why you ever had a problem finding and applying chords on your steel. He is right there with you, guiding you through the neat and easily understood material in the booklet.
Every key has a group of chords common to it.
If you reduce those to simple arithmetic, it's easy. There are only 12 notes comprising octaves. Nothing, when Doug is explaining and demonstrating it on the steel. He takes up where the previous course left off, providing 6ths, 7ths, 9ths, augmented, and diminished chords, bringing them to life on his steel. All these chords are right there on your E9th neck and Doug has tabbed out their locations and plays them along with you.