Is there any reason you took out the link back to b2evolution? If you won't leave that simple courtesy in your skin, then you'll be hard pressed to find anyone involved with the project who is willing to spend time helping you.

actually, I screwed up when editing the page, and couldn't figure out how to get it (the link to B2evolution) back in. Ultimately I just reinstalled the template with everything back where it was.

I still don't know how to put a header image in there though.

You edit the skin that your blog uses. Right now it looks like you're using Custom. Edit the file /skins/custom/_main.php

I understand I have to edit that file.

That was what got me into trouble in the first place. :)

what I_don't_understand is HOW to edit the file properly so that I have a custom header that is shown thorughout my blogs.

The easiest way might actually be to edit your css file. Find this code in /skins/custom/custom.css:

div.pageHeader {
	padding: 1ex;
	margin: 0 1px 1ex 1px;
	border-bottom: 1px solid #ddd;
	text-align: center;
	background: #78a;

Change the last line to something like:

background: #78a url(http://www.yoursite.com/yourimage.jpg);

Experiment until it looks the way you want. You'll need to know a bit about CSS, so here's a tutorial:
http://www.w3schools.com/css/css_intro.asp
This section deals with backgrounds (including background images):
http://www.w3schools.com/css/css_background.asp

Note that anything you place in your skin header section will show up on all blog pages that use that skin (unless you tell it not to).

Thanks a bunch!

Your help is greatly appreciated.