URL Problem

First of all, this is my first time setting up webserver and i’m a total newbie. I’ve been googling around for 2 hours but cant find the exact answer.

My problem is when i load to my web(i.e. http://www.mysite.org),the index.php doest come up but apache’s index.html comes up in the first place. Then I tried http://www.mysite.org/worpdress (using my friend pc), the browser automatically change the URL to http://localhost/wordpress.Could you point me the answer?A how-to or some explanation maybe.