Mike is correct, if the page is a static HTML page (using the .html or .htm file extension) the menu code is added directly to the page.
In a static HTML page, to edit the menu, you need to change the Dreamweaver properties, in the Invisible elements section, set scripts to be visible, this will add a shield icon next to the menu, when you select the shield icon, it will trigger the edit option in the property inspector.
with a php page (using the .php file extension) the menu is added to the page using the php require_once function.