If there’s a space to type in a color, you could put in the hex code for white, which is just #fff. I hope that helps!
Thanks for the quick reply, but there is no space for it. It just gives the four options.
Hmm, then you could hunt this code down if you’d like (probably in your theme’s functions.php) and modify the colors available from there. Or even better – you could create a child theme and override the background color in the child theme’s style sheet.
If some of that doesn’t make sense to you, try doing a search for the phrases you don’t understand and the WordPress help can walk you through it. If none of that makes any sense to you, you may want to just use a different theme.
@ickledave — you can generally change things like background colors in the CSS code — this will give you the basic information about doing so:
http://codex.wordpress.org/CSS
Firebug is a great tool for working with CSS — so you might check that out as well.
It IS a good idea to use a child theme when editing files:
http://codex.wordpress.org/Child_Themes
Thanks for your help – will try setting up a child theme.