Header replacement ? w/o pictures, Kubrick theme.

I have a clean, minimalist header consisting of an xhtml file and a css file. It uses no pictures of any type. I have spent several hours searching for directions and found none. Everything I’ve found assumes another .jpg or other picture will be used. I would like to extract default code from ____ file and the style.css. But, I don’t even know how to locate the right index file and other related files. And, I do not know how to identify code that needs replacement or extraction. If possible, I would like to create for myself a record of keystokes just in case I need to backtrack. Claire did a nice job with :performancing.com/node/429. Will this kind of approach do what I need? What will work? TFYH, frenche