What settings for url are needed while running codeigniter php project

What settings for url are needed while running codeigniter php project

I have started to work in Codeigniter. I have project with name as PRS
with settings in config.php as:
$BASE_URL = "http://".$_SERVER['SERVER_NAME']."/PRS" ;
$DB_HOST = "localhost";
$DB_USER = "root";
$DB_PASSWORD = "mysql";
$DB_NAME = "db1";
In c:windows/system32/drivers/etc/hosts file I have included following line:
127.0.0.1 www.prs.net
But when I am running project with url as http://www.prs.net/PRS/index.php
it is not running my project, it's displaying index.php files code in
browser. So what changes do I need to do?