This is super easy, the first song I learned to play on guitar. 

E  B
A  E
E  B

A 

E  B
C# B A


E  B
C# B  A



You can play this really easily by maintaining the E finger position (x22100) 
and sliding it down to the 6+7 frets to play an A and the 8+9 frets for a B. 
When the C# comes, play it x46600 then slide to x24400 (B) and finally xx2200(A).