I work an under the table job, how do I fill this out?

[Critter]

Your self-employment income was only from cash or personal checks or credit card payments.    
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 or credit card payments (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 get income for (your line of work) screen where you can enter this income as Additional Income.