Hobie, you can place salmon on a cookie sheet. fillet steaks or whole fillet if you have it? The basic is just a thin layer of mayo on the top side. Bake in a 450 oven for 15 min-30 if you have a thicker pieces. You have to be the judge of how cooked you like it. The size of fish you are cooking will determine how long to cook.
Variations? Add some lemon or lime, dill, green onions, wasabi to the mayo. I have even heard of adding lipton onion soup mix to mayo and using that. Not sure of the proportions for that though?
I made the basic recipe for some super health food eating friends one time. They went crazy for it and could not figure out what the "white sauce" coating the top was but LOVED IT! LOL
You can google mayo salmon and come up with some variations.