Chord Csus2 (3rd fret) notes: C, G, C, D and G. You should not play the 6th string.
This chord is played by placing a barre on fret three with your index finger.
Csus2 - C suspended 2nd guitar chord is often noted with non-standard names like C5add2, C2(no3) or C2. Sometimes it's referred to as Cadd9(no3).
1(C), 2(D), 5(G).