This song uses 3 easy chords (D, A, G) and a very simple strumming pattern. This is a great song for a beginner.
With this song, you want your downstroke to be on the downbeat and your upstroke to be on the upbeat or the & of the beat. If you are just learning the song, it helps to strum along with the song while just muting all the strings. This way you can focus all your attention on the rhythm and timing of the song. Then you can go back and learn the chord transitions without worrying about the strumming pattern. I will often just strum the chord one time at the chord change while listening to the song. After making sure I know the rhythm and chord changes, I will then put the two together to actually play the song.
D Chord 