Guitar chords in the key of C major:
C Dm Em F G Am Bdim

Chord Csus4 notes: C, F, G, C and (F). You should not play the 6th string.

The note F on the first string is not required, but can be played on the 1st fret if needed. The string 3 (G) is left open.

C suspended 4th chord's alternative names: Csus, Csus4.

Steps: 1-4-5.
1(C), 4(F), 5(G).