Freelance work is self-employment. You enter it as business income. But you cannot enter business income in TurboTax Free Edition. You will have to upgrade to TurboTax Online Self-Employed, or use any edition of the CD/Download TurboTax software.
You might be able to use the TurboTax Free File Program instead of Free Edition. See the FAQ at the link below for information about TurboTax Free File Program, including the requirements to be able to use it.