Let's try some chord changes from open chords to bar chords first. Play C, Am & G as open chords. F will be the only Bar Chord we will use.
Before you even start strumming through this song, just practice your changes, C to A minor, A minor to F (this is the bar chord), F to G and G back to C. When you feel comfortable with the chord changes use a simple rhythm pattern like the one above. All open chords in this song can be learnt from the Beginners - Basic Chords section.