What

[Main riff]
E|---------------------------------| 
B|---------------------------------| 
G|--------6------------------------| 
D|------------------5---4----------| 
A|---------------------------------| 
E|--0-------5---------4------------| 

[After playing that riff for a while]
E|--------------------| 
B|--------------------| 
G|-----6-----6--------| 
D|-----0-----5--------| 
A|-----5-----5--------| 
E|-----------5--------| 

[Second riff]
E|------------------------------| 
B|------------------------------| 
G|-----6-----6------------------| 
D|-----0-----5------4-------4---| 
A|-----5-----5------0-------4---| 
E|-----------5------0-------4---| 

[As it builds, mess around with feedback and theses two notes]
E|--------------------| 
B|--------------------| 
G|-----4-----6--------| 
D|--------------------| 
A|--------------------| 
E|--------------------|