The HTML code of Backgrounds of profiles can actually be edited. HTML is the language websites are generally written in. Go on your profile and click the green "Edit my presentation" at the very bottom. Then at the bar on the top, click on the blue square icon at the very end, called Edit HTML. You'll find the code of your profile there. Changing the background requires a specific code - a player on the French version of BunnyRace made a website (in French!) with codes for these profiles (http://fichelapino.eklablog.fr/les-codes-html-c238[...]
You'll have to use google translate but you'll be able to find a variety of codes to change your profile. It's a bit of a lengthy process, so good luck!