Is your Testing Server running?
Yes, the server is running. If I click to open the site through Mamp or
manually type in the address it opens it just won't open through dreamweaver
Sounds like your Testing server isn't properly defined in DW yet.
The URL for the document root is http://localhost/.
Note: If you are using the MAMP default ports, use http://localhost:8888/for the URL.
See this tutorial for more details on setting up a PHP environment in DW: