Here's how I do that :

I have a local XAMPP server, installed at c:\xampp\
And the web accessible files should be put at c:\xampp\htdocs\

So, In Dreamweaver, I directly create files and folders in that folder.
For example, working on a site kept inside the folder c:\xampp\htdocs\site6\

I can easily preview it in the browser via http://localhost/site6/

I do same with WAMP

c:\xampp\ => c:\wamp\
c:\xampp\htdocs\ => c:\wamp\www\

Yes but when i try to do that, and i go to preview in firefox for example i receive a message that i should specify a server to run php code, i know that i can access localhost and run it from there, i was wondering if we could simply run preview in firefox and that the script works like a html document, if you know what i mean.

Most probably you don't have the PHP server properly installed.

Which web server base are you using ? Apache or IIS ?
(Apache is recommended for use with PHP)

I'm using this one
Apache Server with PHP and MySQL, including ASP.NET, JSP, Perl and SSL for Windows

and it works fine when i access localhost by writing http://localhost/ in browser.

But when i save php script in webroot folder and i use the preview in feature of dreamweaver it says that i need a php server, that is dreamweaver saying.
when you do that (select preview in) does it display the page immediately, or are you accessing the script by typing localhost in your browser?

Notepad is the main editor. But Dreamweaver is the best.

@Zuly :

I never use the design/preview feature of Dreamweaver.

Best is to use either IE or Firefox to view the output of your PHP files locally.
(using IP : 127.0.0.1 or Hostname : localhost)

Dream Weaver is best editor for php. Even dream weaver is not only most beneficial for php. but it's most affective for asp,css,html,cold fusion,JavaScript.

Easiest PHP editor will be PHP Designer. I can say it's user-friendly.

Hi Ace. You r right. who don't know much coding, uses the softwares.

But the web designers never depend on softwares.
They always think about something new/creative and giving a unique site.

well, I uses notepad/notepad++.

thanks