Since you claim little experience with auto electrics, I suggest you talk to local auto glass shops about having them work on it. I have never dug into a 66 Mercury, but the power windows I am familiar with have a spring that will bite you if you aren’t watching them. Most times, what is wrong with power windows is that the contacts in the switches and the connectors have corroded, and the rollers have become dirty and gummed up. Unless something has broken or become unattached this has a good chance to be your problem.
I have a 53 convertable that I am having one of the window motors rewound as it had fried. Look on the internet for someone that will rewind the armature and/or field windings. I took mine to Eurton Electric in Whitter CA. If you can’t find one in your area they will deal through the mail. Phone: 800-423-4789.
I have a 66 Park Lane that I’ve done several searches for various parts. I’ve noticed the window motors several times both new and rebuilt. I don’t remember who had them but my searches have never been all that exotic. I think you’ll find them.