I'm going to add Videos and Links to this page that concentrate on training and using your Concept 2 properly and in a safe manner. There are some great websites out on the web, so I will of course add links to specific pages that explain more than I ever could or want to, I dislike reinventing the wheel ;)
Has some great images of the muscles worked and when they're worked in relation to the rowing stroke.
http://www.rowingmachineking.com/what-does-a-rowing-machine-do-for-your-body/
I daresay I'll be studying the video above about the Correct Rowing Technique to use often, before I'm competent lol.