You can change the background color in Display Properties. It can be opened using the menu Options → Display Properties → Edit. In the Colors → Other category, you can then define a different color for the background. You can optionally set a background gradient in the General → Graphical Effects category.
The default profile with a white background can be set quickly in the Configuration Manager using the menu Options → Configuration Manager. Select the "Standard with white background" option and set this configuration as current by clicking the button with the blue check mark (see the image).