This is the guitar part. Just listen to the song and you will get the way the riff goes.

G  ---------------------------------------------------------------------------------
D  ----------9--------------------9-------------------9-------------------9---------
A  7-10-9-10---10-9-10----10-9-10---10-9-10---10-9-10---10-9-10---10-9-10---10-9-10-
E  --------------------10-------------------8-------------------7-------------------