Backgrounds are images that can be loaded as the background of a frame. Different frames can contain a different background image, which means that you can create different scenes and settings within a single animation. A background image can be created in MS Paint or other graphics software or downloaded from the internet.
  A background image can be loaded into the animation by clicking 'Load background' in the File menu. Supported image file formats are Bitmap, JPeg, GIF and PNG.

Background Selector

The background selector is similar to the figure selector and provides a way to set the background to one that has already been loaded into the animation.
The background selector is displayed by clicking the 'Background' button in the main window when at least one background has already been loaded.