You don't add losses. You enter your income and expenses. Then Turbo Tax calculates the Net Profit or Loss on Schedule C.
You can enter Self Employment Income into Online Deluxe but if you have any expenses you will have to upgrade to the Premium version. Or use any of the Desktop CD/Download programs. You will get the most help in the Home & Business version.
Where to enter business expenses
https://ttlc.intuit.com/community/entering-importing/help/where-do-i-enter-my-self-employment-busine...
