There are several ways you can get your Ontario fishing license. If you like to do things online, the Ministry of Natural Resources offers you the option of getting your outdoor card and fishing license through this website. If you have never been fishing in Ontario and you live in the USA, find out more about non-resident Ontario fishing licenses here. The basics are that you need an Outdoors Card (good for 3 years) and your fishing license. You need to carry both your Outdoors Card and fishing licence tag whenever you go fishing.You can purchase an 8-day license or an annual license.
You also have the option of purchasing a conservation or a regular limit license. The difference between the two is the catch and possession limit allowed and of course, the cost. Ontario has many different fisheries management zones so know which one you'll be fishing in. Your lodge or outfitter will be able to tell you. Some lodges sell fishing licenses and some do not so make sure you ask. If they don't sell them, many bait and tackle shops across the region do. Follow catch and possession limits and have a great time.
Canadian residents can get more info on obtaining a license here.