When playing the verse you need to lift you finger off the B string whilst playing each chord(listen to the song and you'll know what I mean)

VERSE
   Am  C  F  G
e|--0--0--0--3---|
B|--1--1--1--3---|
G|--2--2--0--0---|
D|--2--3--2--0---|
A|--0--3--3--2---|
E|-----------3---|

CHORUS:
    Dm    Bb(played at end)
e|--1---;----|
B|--3---;-3--|
G|--2---;-3--|
D|--0---;-3--|
A|------;-1--|
E|------;----|
   

VERSE LEAD:
                x3               x1
e|--3-3-3-3-0-0-0--;--1-1-1-1-1-1-0--| 
B|-----------------;-----------------|
G|-----------------;-----------------|
D|-----------------;-----------------|
A|-----------------;-----------------|
E|-----------------;-----------------|

(For the bridge thingy just alternate between playing this chord with down strokes and then struming)
e|--5-----| 
B|--6-----|
G|--7-----|
D|--7-----|
A|--5-----|
E|--------|

OUTRO:(Pick some notes from these)
   Dm/F Dm/E Dm/D#   Dm
e|--1-----1-----1-----1---| x2
B|--3-----3-----3-----3---|
G|--2-----2-----2-----2---|
D|--3-----2-----1-----0---|
A|------------------------|
E|------------------------|
Play Am chord last