Main Riff
E|-------------------------------------|
B|-------------------------------------|
G|--9---9---8---8---7---7---8---8------| Play this throughout the
D|----9—--9---9---9---9---9---9---9----| entire song
A|-------------------------------------|
E|-------------------------------------|
[ Tab from: http://www.guitaretab.com/a/agent-orange/88875.html ]
E|------------------------------------|
B|------------------------------------|
G|------------------------------------|
D|--9999---8888---7777----------------|
A|--9999---8888---7777----------------|
E|--7777---6666---5555----------------|
You can pretty much figure it out on your own.
Good Luck!