This song is fairly easy to play on acoustic guitar. You will need to know the following chords to play this song: G Major, E Minor, C Major, A Minor and D Major (click the hyperlinked chords for lessons on how to play each of the chords).
Guitar Lesson from YouTube:
Marty does a real excellent job of breaking this song down for beginners including how to play the chords from this song as well as the strumming pattern.
As Performed by Bob Marley