All the driving test is conducted by "Drivetest" company and they are licensed by the Government of Ontario to do so. If you want to book a road test you can visit their website www.drivetest.ca
When you are new to Canada, In Toronto, you will first do a written test at any of the "Drivetest" center close to your home. You need to buy Ontario driver's handbook from drivetest center or service ontario sells them too. You can also buy them from Canadiantire or buy it online. Study those books carefully which will includes all the rules of the road and the signs used on the roadway. The book is easy to learn so long as your english language skill is okay. I believe they started allowing people to do the written test in their own language as well.
After you pass the written test, you will be asked to pay money for 5 years license and the road test for "G2 license". Now the clock starts ticking and you have to sucessfully pass both the "G2 License" {City Driving} and then the "G License" {Highway and City Driving}, within 5 years from the date you completed your written test. That is why i suggest sometimes that if you feel you don't want to start driving so early, then you should not do the G1 written test yet. Because once you do the G1 Written test, you have exactly five years to compete the next level G2 and G License. If you do not complete those two driving test within five years, then your driving license will be cancelled and you will have to do the written test starting all over again.
There is also a provision wherein if you have been driving for more than 8 or 10 years in another country beside Canada, prior to applying for a driver license, you will the chance to straight up go for the "G license" test {Highway and City driving test}. If you make it through successfully, then you get the "G license". If not, then you will have to redo starting with your G2 License test and G License test again. Once you pass your G license then you never have to do another driving test again. You then only need to renew your driver's license once every five years and each time they will make you take your photos with their cameras.