When I used to use windows, i just install wamp, and put php code files inside the www folder and navigate to localhost/file_name.php to see that page in action. Now with my new macbook air, php and apache came with the machine, what are the equivalence of "put php files inside www folder" and "navigate to localhost/file_name.php"? How do I do what I used to do in Mac? (also I don't want to reinstall anything, no MAMP please.)
You can look in /etc/apache2/httpd.conf to find more settings and to change it but the default for OSX 10.8 is /Library/WebServer/Documents.
Some more information on how to setup PHP to work with Apache on OSX can be found at: https://discussions.apple.com/docs/DOC-3083