Microsoft Teams has been blurring your background during video calls for almost 2 years, but now you can choose a virtual background or upload your own custom background. To do this:
Use a built-in background in Microsoft Teams
To change your background to one of the built-in images, during a Microsoft Teams video call, click the three-dot menu icon and choose "Show Background Effects" to open the "Background Settings" panel.
Click on an image and then select the "Apply" button.
That's all. The next time someone calls you in Teams, they will now see that image as your virtual background.
Use a custom background in Microsoft Teams
The process for using a custom background is the same except that you use the image you want in a special folder.
In Windows open Windows Explorer on Windows and go to
% Appdata% / Microsoft / Teams / Backgrounds / Uploads . If you are using a Mac,
~ Library / Application Support / Microsoft / Teams / Backgrounds .
Find the image you want to use – maybe a Star Wars image – and copy it into that folder.  Now go back to the Microsoft Teams application, close the "Background Settings" panel if it is open, click the three-dot menu icon on a video call and choose "Show Background Effects".
Your custom photo is available at the bottom of the panel. Select the image and then click the "Apply" button.
You can add as many custom backgrounds as you want and switch between them during calls. However, your choice is not retained on different calls, so you need to apply your wallpaper every time you start a new call.