Are you using the Online version or the Desktop program? Here are some old notes, don't know if they still work.
Open your return and type Schedule C in the Search box. Select the Jump to link.
To add another business or Schedule C….
Go to Federal
Wages and Income,
Then scroll way down to Business Items
Business Income and Expenses - Click the Start or Update button
You should see the Business Summary page that lists your businesses, right below the list you can Add Another Business
