|1||E or G||x||3rd fretfr.||optionalopt.|
Chord Cadd9 notes: C, E, G, D and E or (G). You should not play the 6th string.
The note G on the first string is not required, but can be played on the 3rd fret if needed. The guitar strings 3(G) and 1(G) are left open.
The Cadd9 (C major added 9th) guitar chord is sometimes referred to as Cadd2, depending on the position of the added note and often incorrectly noted as C2.
1(C), 3(E), 5(G), 9(D).