Board Thread:Support Requests - Getting Technical/@comment-1897834-20130408172843/@comment-4018164-20130408183539

You can upload an image to your wiki and then add to your MediaWiki:Wikia.css: While: In case you want to apply a certain style on the search bar in your wiki, can you link to the image that you want to use and describe where you want to position it?
 * XXXXXX is the full image URL.
 * Y (in Ypx) is the distance of the image from the left.
 * Z (in Zpx) is the distance of the image from the top.

P.S. in case you want to add an icon on one end of the search field, you might also need to add padding to move the text so it won't be over the icon.