Originally Posted by: yahtzee101... one of those chords that have numbers in their description (E7 for example) have been mentioned in passing in the videos.

Seventh chords are not covered in GF 1 & 2. In general any number in a chord name refers to adding that scale degree number in the chord along with the 1st, 3rd & 5th scale degree that are the foundation of chord formula.

I did tutorials on Dominant 7ths, Major 7ths, & Minor 7ths:

http://www.guitartricks.com/tutorial.php?input=479
http://www.guitartricks.com/tutorial.php?input=499
http://www.guitartricks.com/tutorial.php?input=500
http://www.guitartricks.com/tutorial.php?input=501