If you are going to be charging over the course of four rolling calendar quarters, the total amount invoiced will be less than 30k, you do not have to register for the GST/HST, HOWEVER, tutoring can fall under exempt supplies, which means you neither charge the tax, or claim the input tax credits for performing your services. Call up the CRA, ask the agent you need some clarifications on exempt supplies when charging the tax, and they will transfer you to the correct department. As for income tax, in either case you would file a T2125 for a self employed individual, and from this, after deducting your expenses, you would have your NET amount. This is the amount you transfer to your T1 and pay income tax off of.
https://www.canada.ca/en/revenue-agency/services/tax/businesses/topics/gst-hst-businesses/charge-gst/charge-gst-hst.html
DO NOT start charging the GST/HST tax unless you have called the CRA. Charging the tax, when you should not, can cause HUGE problems for yourself'
On the T2125, it will ask you if you are a Business, or a Professional. You would indicate you are a Business