If you have business income that was paid either by cash, check or credit card, see the steps below to enter that income onto Schedule C in TurboTax. 

Type Schedule C in the Search box and then select the Jump to link. This will take you to where you can enter any cash, personal checks, credit card payments, or cryptocurrency (Form 1099-K) related to your self-employment. You may first be asked some general questions about your business. After you answer them, you’ll be taken to the Let's enter the income for (your line of work) screen where you can enter this income as Other self-employed Income. 

See the sample screenshot attached.