As a subcontractor who received a 1099, you are considered to be self-employed for tax purposes and should file schedule C.

To get to the input screens for your business:

• Once signed into your account, click on Search at the top of the screen
• Input "schedule c" into the search box and hit Enter
• The first link available should be Jump to schedule c - click on this link
• You will be taken to the screens to enter your income, business information, and expenses