This is a great punk rock song by the Clash. It uses three easy chords. D, G, and A. If you know those three chords you can play a ton of great easy stuff.
This is a good tab and chord website. It has this song in a fairly good format.
http://www.ultimate-guitar.com/tabs/c/clash/i_fought_the_law_crd.htm
I like to do the change form G to D really quickly. The tempo is rather fast.
For our next easy guitar song we will do the Lynyrd Skynard classic Sweet Home Alabama.
Rock On!!