Guitar chords in the key of C major:
Chord Cmaj9 v.2 notes: C, D, G, B and E. You should not play the 6th string.
The strings 4(D), 3(G), 2(B) and 1(E) are left open.
C major 9th guitar chord's alternative names: Cmaj9, CM9, Cmaj7(9).
1(C), 3(E), 5(G), 7(B), 9(D).