You can load alternate header footers instead of your global header or footer for any category but that means you need to create such a header or footer file and then place the proper full server path to those files including name where asked there.
well what it means is you load an alternate header instead of the default global header. This is a feature of the application when not integrated with vbulletin.
You would need to actually create the actual header file so cat501.htm and load the full server path including filename in the space for header. That file you create if all you want your header for that category to be is some image you can make the contents of your header file an html img tag to some image sure.