In 2019 I made commission from my parents bed and breakfast for taking reservations. I made 15% of their profits. I was not on the books but would like to claim this money. Do I need a DBA? How do I g

No, no DBA is necessary.

When you work "off-the-books," that's considered to be self-employment income -- it's reported as being in business for yourself. 

On your federal return, you report these earnings on Schedule C, and you'll pay self-employment taxes using Schedule SE.

For more information, please see the TurboTax Help article "How do I report income from self-employment?".