With a lot of help from deltafoxtrot I succeeded in making the changes I wanted in Connections (dianevacca.wordpress.com).
I've changed the code for the better-header.gif and the header image:
background:#fff url('http://s.wordpress.com/wp-content/themes/pub/connections/img/blue-header.gif') no-repeat bottom;
border:#fc9 0 solid;
background:#54659B url('http://s.wordpress.com/wp-content/themes/pub/connections/img/laundry-txt.jpg') center repeat-y;
margin:2px 0 0 10px;
But I can't get both to load at the same time. I either get all blue or my header image with the original better-header.gif.
Another question: does page navigation mean that you can add pages to your blog? And if so, how to do it?
I haven't purchased the CSS upgrade yet-- Should I work my problems out first using the Preview function or bite the bullet? I have the nagging suspicion that after purchasing the upgrade I may find out that I would be better off with another template. I think the upgrade can be applied to only one template. Is that true?