How to register for private computer repair service ib toronto.?

How to register for private computer repair service ib toronto.?
I am certified in a+ computer service techician. I want to start my on private business in toronto, Canada. But I want to start it legally, so could some please one guide me how to register business through ontario law.
So that I can pay my taxes. Please help me out, m desperately looking for help. God bless you.
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