I wrap my turkey in aluminum foil and usually cook it 20 minutes per pound. It's easier if you buy one of those turkeys with a pop-up timer in them...then you know for sure.
Covering the turkey with foil keeps it from drying out. If you don't use foil, the skin on the top is going to be very crisp and dry. I'd suggest covering it at least the first hour, but I usually cover mine until the top is a pleasing color.
About the time, the average rule of thumb is 15 - 20 minutes per pound at 325 - 350 depending on your oven. If you're going to stuff your bird, that can add an additional 20-45 minutes per pound.
Whenever I am faced with something I haven't cooked before (or in a long time) I go to Allrecipes.com. There are lots and lots of recipes, and I just sort through until I find one I like.
This video explains in detail how to cook a turkey in your oven.