Drop C

Main riff:
D------------------------------|
A------------------------------|
F------------------------------|
C--3-000000000-3-4-0000000-4-4-|  [x3]
G--3-000000000-3-4-0000000-4-4-|
C--3-000000000-3-4-0000000-4-4-|

on forth time
----------------|
----------------|
----------------|
--3-7-6-5-3-5-3-|
--3-7-6-5-3-5-3-|
--3-7-6-5-3-5-3-|

bridge
D----------|
A----------|
F----------|
C---7-7-6--|
G---7-7-6--|
C---7-7-6--|

Every other part in the song is rooted in one of these riffs.  Good Luck!