If you are referring to the PC version you will have to log into your router and set up a port forward to the PC you are hosting the server from. To log in to the router simply type 192.168.1.1 in your address bar and use "admin" for the username and "password" or "password1" for the password. You will find port forwarding under the Firewall section.
Written by Robert Ronnell - seth
Last updated on 02.21.08