Build your website using Dreamweaver. Fireworks is for working with graphics. Flash is for animation.
Use graphics apps to create graphics only.
Use DW to build your web pages - HTML and CSS code.
Insert Flash media into HTML pages when needed. Provide alternate content for devices that don't support Flash.
Flash only sites are not user- and search engine friendly, also not supported by many devices.
Have a look at this 2-part tutorial:
Taking a Fireworks (or Photoshop) comp to a CSS based layout in DW - Part 1