Hi Mary,
You can edit the background colour of the footer in the source.
At the top left of the footer editing screen, click the "SRC" button. You will be presented with the HTML. In here you can edit the background colour with something similar to this:
<table align="center" bgcolor="#FFFFFF">
This is a white background, you will need to find the correct hex ref for the colour you want.
Hope this helps,
Will Oliver