Questions About Custom Theme

I manage a Web site for a park. The site is designed in Dreamweaver using templates.

I’d like to incorporate WordPress into the site so it looks built-in. The template is a standard top header, left navigation (some DHTML) and a footer. The main content – and the blog content – would reside in the current editable area of the site.

I have some skills, but can someone point me in the direction of some sections in the Web manual or provide some additional information?

Thanks in advance.