Riff 1 :
E|-------------------|
B|-------------------|
G|-------------------|
D|-9999-10-----------|
A|-9999-10-----------|
E|-7777-8---8-7-6----|

Played 4 times first and on the 4th do this instead:


E|---------------------|
B|---------------------|
G|---------------------|
D|-9999-10-------------|
A|-9999-10-------------|
E|-7777-8---8-7-9-10---|

Riff 2:
E|-------------------|
B|-------------------|
G|-------------------|
D|-9999--------------|
A|-9999--------------|
E|-7777-----8-7-6----|

Played 4 times first and on the 4th do this instead:

E|--------------------|
B|--------------------|
G|----------3---------|
D|-999--77--3---------|
A|-999--77--1---------|
E|-777--55------------|

The 2 riffs are very much alike, exept for the 4th time they're played

Now when the clapping and drums start (after playing both riffs) you replay the first 
riff, and then play this last riff: (Let's call this last riff, riff 3)

Riff 3:

E|-------------------|
B|-------------------|
G|-------------------|
D|-9999-10-----------|
A|-9999-10-----------|
E|-7777-8---8-7-6----|

Played 4 times first and on the 4th do this instead:

E|--------|
B|--------|
G|--------|
D|-9999---|
A|-9999---|
E|-7777---|