If you're under age 18, you'll need a hunter education certificate. You don't need a fancy, expensive gun to hunt waterfowl. And with the weather you'll be hunting in, you probably wouldn't want to risk an expensive gun anyway. Pump shotguns are reliable and relatively inexpensive. Auto-loading shotguns are more expensive, heavier and require more maintenance, but many hunters prefer them for their quick shooting ability.
Double barrels can be the most expensive, but some hunters prefer their feel and simplicity.
Make sure your gun is approved for steel shot. If you're not sure, take it to a gunsmith. Gun clubs are an excellent way to get practice and find new hunting partners. That means shooting different shot shell loads through your gun at a large target at 40 yards. Change chokes and see how and where the pattern of shot hits the target.