You could go about this a couple of ways, depending on what scripting languages you are going to use. If you are using a server-side language such as PHP or ASP, you could use server side includes or database interaction to integrate your nav bar from a single location into multiple pages.
If you are using straight HTML, you could employ the 'old-school' method by using frames to create a navigation pane. The W3C has a good tutorial for learning about frames here.
Why not use a template within Dreamweaver. With that, you make how you want all o fyour pages to look (provided the design is the same). You make an editable region within the templated page that will house your page content. When you update your nav bar, you do it on the template and it will update all of the pages that the template is applied to.