help newbie user can't get controller to work

[eluser]gloosemo[/eluser]
Appreciate any help.

i just installed codeigniter for the first time. I'm trying to get the stupid user guide example to work and can't do it.

i saved the following file blog.php in the application controllers directory:

<?php
class Blog extends CI_Controller {

public function index()
{
echo 'Hello World!';
}
}
?>

I then put my website onto my localhost server on my computer. The application and system files are in the and attempt to log

http://localhost/index.php/blog.php

it just displays index.php content (a page i wrote before codeigniter), no 'Hello World' anywhere. what am i doing wrong??