Step 1: Navigate to Account > Locations
Step 2: When you get to the locations page, hit the edit button.
When you hit edit, there is an area to upload a 500x500 pixel site logo. Once you have uploaded it, your site logo will appear on your website.
Hooray! Your logo will be automatically added to your website!
*note that if this does not update on your site and you have a site from 2015 or earlier you may have to submit a design request to update your logo.