It's really very simple... caualtr basically said it all..
Just make sure you have a wiring harness (most audio retailers carry or will order the proper one for your truck) and a mounting bracket, since most decks won't fit into the stock opening as they are.
Aim for about an hour of work, start to finish. You'll cut that time in half after you've done it once.
Fords are great for this since you don't have to pull any of the dash off, like most vehicles make you do.
You will also want to have a set of wire cutter/crimpers

(Everyone has this tool laying around)
and a package of butt connectors

on hand. Just match the wires from your wiring harness that you buy to the wires from your new deck and crimp them in the butt connectors. The harness will plug into the stock plugs already in the truck, so you don't have to cut anything.
Just make sure you have everything you need before you start and it will go smoothely.
Good luck.