Media upload problem - where do I "hard code"?

Hi there, it seems I am having a problem with being able to upload media via the Wordpress media upload function. This means I cannot customize the theme to use my logo.

I need to sort out with my webhost how and why the upload problem persists. In the mean time, is there a way I could "hard code" my header logo in a .css or templatefile? I know I can do this I just do not know which one and what specific css class or to use.