If your rideshare business is not incorporated, then you would need to your income & expenses on your T1 tax return. So you would need to go back and add it to the same return that you used to report your employment income. 

If your business is incorporated, you'll need to file a separate T2 return for it, using TurboTax Business Inc. 

Hi, thanks for replying.

Uber/Lyft is just my side income.  Are you saying I can't use another tax software e.g. Turbo Tax to file my rideshare income?  I just wanted to file it separately using Turbo Tax self-employed.

No. If your you need to fill out the T2125 self-employment form, it must be part of your regular T1 tax return. If you try to file another T1 return, it will be rejected by the CRA because you have already filed another return for the tax year.