By default on kidzsearch, the background is plain white. Although this may look nice, sometimes somebody wants a little bit more fun to theyre page! This can be from batman to my little pony, and are preset from Kidzsearch, and preapproved! (This is why many people put the request for certain images) Some people have cars, elmo, superman, flowers, pikachu, you name it!
How you change your background is go to the settings on the main page. As you can see, I have a beach. If you click the picture you want off of the selection, next time you go to kidzsearch you may be given an option that says "search settings applied" then click continue and enjoy!
I pointed out where it is with the red arrow. Hope this has been some help!