What ever you do get a Ford one. Not a repo. one. I got a repo armrest from 5.0 restore. It is cheap china crap. I once in a while see Ford ones on ebay cause people buy them and it's a pain to put them on. May have to paint it. 5.0 restore might have new Ford ones.
50resto.com is a good place... now onto the original question. there are about 10 screws, that are kind of a pain to get to, they are right next to the windshield. i know for sure there are two in each of the heat vents, and one or two more next to the door jamb, another hard one to get to. don't yank and pull to much, once you've gotten all the screws it should slide right off.
-aj