Riff A
G --------------------------- 2h4 ------------------------------------------------------------------------ 2h4 -------------------------
D ------------------- 2h4 ----------- 2h4---------- no rest inbetween ------------------ 2h4 ----------- 2h4 ----------------
A ----------- 2h4 ------------------------------------------------------------------------2h4 ------------------------------------------
E ------------------------------------------------------------------------------------------------------------------------------------------
Riff B
G ------------------------------------------------------------------------------------------------------------------------------------------
D ------------------------------------------------------------------------------------------------------------------------------------------
A -- 4444444444444444 --- 2222222222222222 --- 44 XX 44 XX 44 XX 44 --- 22 XX 22 XX 22 XX 22 ---
E ------------------------------------------------------------------------------------------------------------------------------------------

You just play these two riffs throughout the whole song.
The muting is easy once you get the timing right.