Once you've did that, and started the game in server mode, people can connect to your Internet address. They have to start the game in client mode and give your Internet IP address with the -ip command line option. Your Internet IP is assigned by your service provider - it's not the same as your local server IP. You can find your Internet IP through websites like www.whatismyip.com. Note that you can probably not connect to your own Internet IP unless your router supports NAT loopback. So you need to ask other people to test the connection.