There are two edible parts of a duck, whether wild or farm raised: the breast, and the leg and thigh.
Some people like to roast the whole bird, but I prefer just to remove the breast and the leg, and then use the carcass for gibier or duck stock.
Duck breasts, generally, are cooked by scoring then searing the skin side in a hot skillet for a few minutes, sizzling the meat side briefly, then roasting at 400 for 5-10 minutes. It should be rare-medium rare. (I once ate a whole raw, warmed Bluebill. Sushi. Wasn't too bad, but a bit fishy. I wanted to take "rare" to the limit.)
Then comes the sauce. Here are a few of my favorite ideas:
1. I like a cherry sauce, like this one (which was meant for venison), or this one. Here's a fancy Sweet Cherry Sauce.
2. This pomegranite sauce would be good for venison too.
3. Caramelized figs are a classic with duck breast.
4. Emeril does a simple pan roast. Trouble with that for me is the danger of overcooking.
5. I also like a sauce made with a gibier base, with some halved cherry tomatoes and chopped Italian olives and a little vinegar.
Duck legs are another matter, because they are tough and stringy like pheasant legs. Both do very well for confit, if you want to take the trouble. An alternative is to braise the legs. Some ideas:
Wine-braised duck legs
Braised Duck Legs for idiots