Where should PHP files be stored?

[nthom58]

I have downloaded xampp and have both Apache and MYSQL running quiet well. I am trying to set up a PHP development environment for Dreamweaver without too much success simply because I cannot work out what files should be in what folder. For example where is the "testing server located, is it c:\xampp\htdocs or is it in Apache? Similarly where is the web server document root located? When I try to connect to a database through Dreamweaver I am told that the testing server does not map to http://htdocs/MyWebApp2/.Also when I create a PHP in dreamweaver and preview in a browser I get similar messages. As you can gather I cannot picture the whole layout so that I can create a PHP page and know where the relevant PHP file should sit and how the PHP , server , and the web page comes together. Any ideas links would be most welcome.