How do you you play chords on a guitar?
Typically, the 6 string guitar is tuned on the notes EADGBE. If
you strum across those strings without touching the fretboard you
would have a Em7sus chord.
Building the chord, we have root (E) 3rd (G) 5th (B) 7th (D) and
the added 4 (A) which is a suspension note.
To make other chords, you learn the theory of how to make a
chord and then use your fingers to press down and change the open
strings to something else that fits the chord that you are trying
Get a guitar chord chart and use that but it would help you
tremendously to learn the theory to understand why each chord is
what it is.