i have a fairly foolproof recipe I use called "7 minute Salmon"

one 4-6 OZ salmon filet (run your fingers over the filet and remove any pin bones you find)
salt and pepper
1/4 cup light Italian bottled salad dressing
1 tsp butter (preferably unsalted, but if not, just don't use much additional salt)

Place the filet(s) in a ceramic microwave safe dish with lid, season with salt and pepper and pour the dressing over (if using 2 filets, increase the amount of dressing) and let the fish sit, flesh side down for about 15 minutes

microwave on high, covered until fish is firm and pink (about 7 minutes for one filet, 9 minutes for 2)

let rest for a minute then transfer to a serving plate. add the butter (increase amount proportionally to the amount you increased salad dressing) to the cooking dish and stir with a wooden spoon until melted then pour over fish and serve immediately

you can finish it off with a squeeze of fresh lemon juice too, or a grate of Romano but neither are necessary