insert header into retro-fitted theme?

Hi there,

For some reason, there is no “header” section in the appearance menu in the backend (using retro-fitted theme that usually supports headers). So I thought I’d try it with CSS.

This is the stylesheet:
#header{overflow:hidden;width:100%;height:60px;padding:20px 0;background:url(images/header.png) repeat-x 0 0;border-bottom:10px solid #ce3000}#header .wrap{width:980px;margin:0 auto}

Does anyone know where to upload the header in the backend and where to insert the code in the stylesheet or the header.php section?

Thanks for any help!