In Google Docs, you can add watermark, picture and solid color background to your page. Learn how to insert Background Images in Google Docs.

Cick on Choose to accept the new background. If you want to add your own image as a background click on the plus sign as above, but use the Finder window that opens to locate your chosen image.

It is quite easy to learn how to change your background in Zoom and Microsoft Teams. Here's how to do it on mobile and desktop/laptop.