I used a mileage app Everlance to track mileage for my door dash driving

To report your Business Income and Expenses, type 'Schedule C' in the Search area, then 'Jump to schedule c'.

 

You enter some info on your Business, then you'll see categories for Income and Expenses (where Vehicle is listed).

 

Enter some info on your Business Vehicle, and you'll be able to choose Standard Mileage and enter your mileage numbers.

 

Here's some info on Using a Vehicle for Business.