The virtual background feature allows you to display an image or video as your background during a Zoom Meeting. This feature works best with a green screen and uniform lighting, to allow Zoom to detect the difference between you and your background. 

You can also upload your own images or videos as a virtual background. There are no size restrictions when adding your own virtual backgrounds, but we recommend cropping the image to match the aspect ratio of your camera before uploading it.

Example: If your camera is set to 16:9, an image of 1280 pixels by 720 px or 1920 pixels by 1080 pixels would work well.

This video will walk you through the steps:

For more information, including prerequisites CLICK HERE

Source: "Zoom"