You can use the Autolite plugs as well. I believe but may be wrong... but the autolite uses copper and platinum, where the motorcraft uses strictly platinum for the core and electrode. The price of the plugs is fair from Ford and they do the job well. I've heard people have had issues with other brands but I have personally only used Motorcraft with my Explorer.
To change your plugs, take your cover off, then take out the air intake tube. From there, get a deep socket and your golden. I would recommend using an air compressor to blow out the debris that will be on top of the plugs before you remove them.
The cover has the 2 nuts from the alternator, and the rear has a tube in the back held on by a clip. You can see this from the rear. Besides that, it sits on two balls so just pull it off.