In this video Mark Donovan of http://www.homeadditionplus.com shows how to replace exterior window trim, or more specifically, rot damaged window trim.

In his case he had to replace a rotten exterior window trim piece that was punky from water damage.

In the video Mark shows in detail how to remove rotten exterior window trim, and then how to replace the old window trim with new pre-primed 1x4 trim.

The video shows every step in the process from removing the rot damaged window trim to installing new window trim.