This documentation will highlight the steps required to change the background of your camera in Webex Meetings and Events. This functionality does not currently exist in Webex Trainings.
The ability to upload custom virtual backgrounds will be coming in Update 40.8 (will be released on August 4, 2020)
System Requirements for Backgrounds
Please note that virtual backgrounds currently require a large amount of resources from your CPU and you may end up with the following message:
If you're unsure your system can handle this feature, please reference the system requirements documentation found here
Before joining, select Change background and then the selected change you would like to apply (Blur in the below image)
Changing Your Background After Joining a Meeting
Method 3: Navigate towards the top left of your window / top bar on a mac and to select Audio followed by either Change Virtual Background or Speaker, Microphone, and Camera.