Editing based on your clarifications:
You already have OHIP, and you're looking for supplemental insurance for the other expenses. Try insurance brokers in the yellow pages, or follow the links from the Insurance Canada industry website that I provided. Make a list of what expenses you would want help with - dentistry? chiropractic and physiotherapy? glasses? hearing aids? private room in the hospital? prescription drugs? wheelchairs and accessibility renovations?, and try to estimate what you'd spend on those things in a year or five years if you were paying for them yourself. Keep that in mind when you get quotes from various insurance companies. (With this kind of insurance, you don't just pay the premiums; you'll probably also have to pay some kind of deductible each year, or there might be a maximum charge, or a certain percentage of your expenses that they would pay. Their application forms might ask you questions about your existing health conditions, so that they can decide what to charge you.
Unless you have an employer paying part of the premiums for you, it is unlikely that you would save money buying supplemental health insurance. So buy it only for the really big things that you couldn't afford to pay for.
leaving my first answer, as good general background:
Have you lived in Ontario for more than three months? You are eligible for OHIP, the basic free health insurance program provided through the government, as soon as you've lived in the province for three months. Go through the questions on the first link to find out how to get a card.
OHIP doesn't cover things like eyeglasses, dentistry, or prescription medication. Lots of private insurance companies sell *supplemental medical* insurance for those extra things. Your employer might have a plan which they would give you or let you pay for. If you're a student, your university or college probably has a supplemental medical package for students. Or if you want to buy that kind of insurance on your own rather than just paying for your glasses, dental work, and son on, you can shop around for various commercial insurance companies and pick the kinds of coverage you want.