Play main riff till 3:20, then play the fill, then back to main riff.

Main Riff
G-------------------6--
D--------6-8------8----
A------------3456------
E---3456---------------

fill at 3:20
G--10-8-8-6-6h8p6---------
D----------------h8-6-----
A---------------------4---
E-----------------------6-