If you have already filed your personal T1 General tax return and did not include your Self-Employment or Business Income, you'll need to do a ReFile to include the T2125 - Statement of Business Activities with that tax return.
Only if you have an Incorporated or Limited business do you file a separate tax return. Small business owners include this form with their personal tax return. When you complete the T2125 form, (found in the Self-Employment section of TurboTax), you will report any income and expenses that you incurred with your side business and the "Net Income" will be added to any other income you incurred in 2019.
You will also need to pay CPP premiums on the net income that exceeds $3,500.
Here's a little more information you may find helpful: You May Have Business Income and Not Even Know it!
