So I'm totally new to WordPress so forgive me if any of this is bad information. I am trying the same thing (to get the nav bar to go to the top of the page.) I started with the Twenty Ten default theme and I'm working from there. Here is my site http://www.casandravallee.com/dev. (its a work in progress and my alignment is currently messed up so forgive me.)
Ok so what I've learned so far, first make a child theme. Look it up on this site they have great instructions. Then you can copy files into your child theme and mess with them.
So I copied the header.php file and just moved the <div id="access" role="navigation"> part of the code to the top so its above the <div id="branding" role="banner"> . So far it moved the nav bar to the top above the banner. I still have to pretty it up but at least its in the right place now.
Hope this helps someone. Here is my header.php code so far.
[Code moderated as per the Forum Rules. Please use the pastebin]