Add9 chords are formed when a 9th is added to the 1st, 3rd, and 5th intervals of a major or minor chord.

add9 open chord root on 6th string

add9 Chord – Open

add9 chord root on 5th string

add9 Chord – Form 3

add9 chord root on 5th string

add9 Chord – Form 2

add9 open chord root on 6th string

add9 Chord – Open

add9 chord root on 4th string

add9 Chord – Form 1