Can you please explain it to me in Detail about becoming a car dealer in ontario and selling cars privately?

I want to become a "used" car dealer and start selling cars privately. I am thinking of buying say 3-5 cars around 3k-20k range. Keep the cars in my home garage. and sell it privately by listing it on autotrader, craiglist and other websites. I have quite a few questions regarding this:

Can it be done?

Is it profitable?

where do most used car dealers buy their cars from? can you list the sites?

how does the whole process works (from buying a used car to selling car), please explain it to me in complete detail?

If you buy the cars from an auction, can u test drive and have your mechanic look at it or find out good and bad about the car prior to bidding?

I am very new at this and dont know most things about this business but very eager to learn and hopefully run a small business.

thank u for taking the time to read and answering questions