I know that a lot of those who have found Farseer Physics Engine have had trouble figuring out what exactly is needed to create a Farseer Physics enabled game. I took some time to create a very simple game in XNA with only what is absolutely necessary to
get physics to work.
You can find it as the first link (bold text) on our tutorials page:
Hope that helps some of our new users to start using Farseer Physics.