Your T4A should be entered first in TurboTax, then you go to Income > click directly on Self Employment > check the box  - "Professional, Commission, and/or Other type of Business" (if it is not already) and proceed to the page T2125 Business Summary.

You must now "Edit" the business that appears with your T4A commissions which has transferred there. In the Free version of TurboTax your expenses will all be entered on the same page.