The etrailer video mentioned above does do a good job of explaining some principles of most WD hitches.
Most dealers carry one or two brands of hitches, and will recommend what they have to sell. I would recommend looking into the Andersen hitches, as I went with that and am very pleased with the results. They have built-in sway control so you don't have to worry about disconnecting anything to back up. They are also very clean and easy to connect and disconnect, and weigh less than conventional WD hitches, but certainly have a high capacity. They are super easy to adjust.
Andersens can be bought from some dealers, or from the factory in Idaho Falls, Idaho. (I bought mine from some place in Nebraska before I found out the factory was only 50 miles from where I live!)
You can see Andersen's video on installing their trailer hitch here:
Disclaimer: I have no relationship to Andersen and make no profit from this recommendation ...
Roger