Watch the JAM: Triads and Seventh Chords 1 online guitar lesson by Susan Mazer from Hands On Guitar: Beyond Beginner
The chords move fairly quickly in this tune, so if you miss a chord jump back in when you find your place. Practice the right hand strumming pattern enough that your hand is on “auto pilot” and you can play without thinking. If the strumming is still difficult, the first time through you can just use two down strums per measure instead of the pattern given. Have fun!