I have never hosted game, but I know if you want to host any game or any webserver application, you need to let your router know. You will need 3 informations: your PC's local IP address, your router local address and router admin info.
First open internet explorer and type in your router address, for example: 192.168.1.1 Then it will ask for your access code. If you have never done it, the username should be blank and pass should be admin or vice versa. Then go to port forwarding or DMZ tab, type in one of many blank field your PC's local IP address ( for example: 192.168.1.7). And the port you should put a port number. Normally for webserver, it should be 80, for email server, it should be 25, for other you just put something like 8000 or anything you like or you can just look it up from the list here for your pacific game: http://portforward.com/cports.htm
That is basic step to host application on your PC. When your friend want to access your server, they should type in your global IP address then your port number that you setted. For example: http://87.23.145.55:8000 . If this doesnt help you, Nicole should know and help you. Good luck mon.