This is played throughout the entire song, although it's obviously done vocally. 
It's as simple as 1,2,3. Enjoy.


     E  E  E  E  E  E  E  E  E  E  E  E     E  E  E  E  E  E  E  E  E  E  E  E    
E||--------------------------------------|-----------------------------1--------||
B||--1-----------------2-----------------|--2-----------------2-----------4--2--||
G||-----2-----------2-----3-----------3--|-----1-----------1-----1--------------||
D||--------3-----3-----------4-----4-----|--------3-----3-----------3-----------||
A||-----------3-----------------4--------|-----------4--------------------------||
E||--------------------------------------|--------------------------------------||