try for your own local client the 127.0.0.1.
open server.dat en change the ip of your server into 127.0.0.1
then host the game itself on your ip-adres.
make sure u have static ip-adress, search on google howto.
Port forward all ports.
to find your static-ip :
open cmd, type ipconfig and at ip-adress, there is your static ip.
goodluck
sorry for my typing of english, i'm dutch