Main Groove:
1st: Place pinky finger on the 7th fret of the
     B/2nd string and leave it there for the first
     part of the main riff, while fretting the notes
     on the G/3rd string with your index finger.

|----------------0---------------0--------|
|--------7--7--7-7-------7--7--7-7--------|
|--------4--5--7-7-------4-/5--7-7--------|
|--------0--0--0-0-------0--0--0-0--------|
|-----------------------------------------|
|-----------------------------------------|
                 ^  quick strum  ^

2nd: Then move pinky finger up to the 8th fret
     on the B/2nd string and leave it there for
     the second part of the main riff, & repeat
     alternate pickin' & struming technique.

|----------------0---------------0--------|
|--------8--8--8-8-------8--8--8-8--------|
|--------4--5--7-7-------4-/5--7-7--------|
|--------0--0--0-0-------0--0--0-0--------|
|-----------------------------------------|
|-----------------------------------------|
                 ^  quick strum  ^

Bridge:
Am (x02210@1) Bm (x24432@1) G(x2) (320003@1)Am (x02210@1) Bm (x24432@1) Am(hold) (x02210@1)  G (320003@1)|---5---7---3---|
|---5---7---3---|
|---5---7---4---|
|---7---9---5---|
|---7---9---5---|
|---5---7---3---|
    Am (x02210@1)Bm (x24432@1)G (320003@1)