If you're on windows, you can either open the 'Command Prompt' by opening the Run program and typing 'cmd', or by searching in your 'Accessories' folder, then typing 'ipconfig' and retrieving the IP. Otherwise, go to
http://www.whatsmyip.org and the ip will be posted there for you. Then you should go into your server.cfg, find out what your port is, and add that onto the end of your IP address.
Example:
whatsmyip.org tells me my ip is: 52.82.155.62
My server.cfg says my port is: 1624
My server IP is therefore: 52.82.155.62:1624
Note: This is only if you're running a localhost, and not using a dedicated host such as Volt-Host.