A custom background is a great way to add details to your site no one else will have. You can upload a custom background in just a few steps.
First, click on your website icon, either Portfolio or Builder. From there, hover over design and click on site background.
On the site background page, select the radio button for custom background and you will see an option for add files where you can upload your background image file.
Note: Your background image file must be in JPG or PNG format. The maximum, and recommended, size is 3000x1730 pixels.
Once your background is uploaded, click on save changes.
If you're using the Portfolio, make sure to go to publish and click on publish now to make your changes live.