You have to listen to the song carefully to know when to play what, 
put its pretty random 
 
RIFF#1 
G:------------------------: 
D:--------0---------------: 
A:-2020202-20202----------: 
E:---------------0-122----: 
 
RIFF#2 
G:-------------------: 
D:-------------------: 
A:-20202----20202----: 
E:-------------------: 
 
RIFF#3 
G:----------------------------------: 
D:----------------------------------: 
A:-222222200-0000-----------0--0----: 
E:---------------33-333322-2-2------: 
 
Listen to the song to see where to play it. its a really good song so try itout.