The number it is referring to appears to be your IP number.

This numbers easy enough to find, just visit WhatIsMyIP.com - 75.126.211.156

The 4 number string you see on the page ie 111.22.33.44 is your IP address. If you are hosting, then your mate needs your number to put in his DIRECT CONNECTION box. If he is hosting then he must obtain his IP address and you must enter it in your box.

You may need to forward ports if you have routers, information about this can be gained from PortForward.com - Free Help Setting up Your Router or Firewall

Hope this helps.