adding a new header template for static pages

Hello,

I currently have my blog in a virtual /blog/ directory. I want the blog header to be different from the headers on the other pages off my site.

I know how to create new templates and where to put them in the themes folder. What I am unsure of is how to code the page.php file properly so that it adds the alternate header template (headernew.php) and not header.php.

Thanks,
BW