I'm not sure I understand your question.
to add Power CMS Builder to your site, open a php page, select content on the page that you want to convert to a content area and go to WebAssist -> CMS -> Add content to power CMS.
If you define the testing server in Dreamweavers site definition to use your XAMP server, you can test the pages on your local xampp server.
see the "Defining a Dynamic Site in Dreamweaver" tutorial on the learning resources page:
tutorials.php