trying to add box on header. Not working

Hi,

I started an art blog http://www.project-inspire.net. it worked very nice… until i thought of adding adsense to it. the site looks nice but the advertising banner is very intrusive so i am trying to add a black banner behind it. it is a nightmare. maybe because of the peculiar dynamic platform i chose for my blog. can anyone help? and i have a second problem with the pages in the menu. the items on the menu are supposed to show only items labeled under the same category. but nothing is happening. i need help here too. Pleaaase. i am getting hopeless