This is how I think it goes....

Main Riff 1 (It starts out quiet for a few measures, 
then gets louder.)

G-----------------------------------------------------------------------------
D-----------------------------------------------------------------------------
A---------2----------------4-------2----------------------------------------
E--4-------------2-----------------------------------------------------------
B-----------------------------------------------------------------------------

Main Riff 2 (This is only a slight variation from Riff 
1)

G--------------------------------------------------------------------------------
D--------------------------------------------------------------------------------
A----------------1--2------2-------2----------------4-----4-4---4----2--------
E--4--------2 
4-------------------------4----4--4--------------------------4---
B--------------------------------------------------------------------------------

Chorus and Bridge (There is a slight variation between 
the Chorus and Bridge, but it's only an extra note or 
two, so it couldn't be very hard for you to figure 
out.)

G-------------------------------------------------------------------------------
D------------------------------------------------------------------------------
A------------------2--22---2-------------------------------------------------
E--------4---4--------------------2---2---2----------------------------------
B------------------------------------------------22---2---2-----2-2---------