Most beginner guitarists start by learning these fifteen chords,
often called the "open chords" because they make use
of open strings and are thus easy to play.
A |
A7 |
Am |
B7 |
C |
D |
D7 |
Dm |
E |
E7 |
Em |
F |
G |
G7 |
For fingerings, have a look at wikipedia.
You can also consult any book on beginner guitar. For instance,
the chord charts on pages of 74-75 of Ralph Denyer's ubiquitous
Guitar Handbook are really nice (though I don't recommend this
book otherwise.)
Here are the most common keys played by beginner guitarists,
with the open chords you can use in them. Pick a key and try
the chords within it. 'Diatonic' chords sound nice together
in any order and in any combination. The other chords are more
dissonant, but they've become familiar through years of common
usage. Trust your ears!