Song is simply three chords

C5  C5  A5


The pattern of the entire song is as follows...

 C5  C5  A5  C5  C5

pluck the bass note first followed by the D(3)  G(4) B(5) strings of the chord


Listen to the song for the rhythm. It can be a great teacher if you're a beginner.

Enjoy!
Hope this helps.