No, not the media tab...that is only for images in your site's content. Any images pertaining to the theme need to be uploaded to the images directory either through the cpanel or ftp.
And it doesn't go into the header.php, the code for the header image is in style.css as seen in the code below:
- Code:
.header { background: #ebe1c8 url(images/header.jpg) no-repeat; width: 990px; height: 140px; margin: 0 auto 10px auto; padding: 0; float: left; border-bottom: #3f3013 3px double; }
Just edit this code to put the filename of the image you're using (currently header.jpg).