I wentto gnugk site and found the file.
Go to downloads and get “windows executable” it eill give you a list of sites.
Download the file. It is about three MB.
Unzip the file. Install it on the computer that have the public I.P. addrees, the one conected to the internet with a fix I.P.
Once it is installed, you will have two icons on the desktop. One will let you start/stop the aplication.
The other (monnitor )will let you monitor who is registering or unregistering on your gatekeeper.
Point your gateways to the I.P. address of that P.C.
Try to make calls betwen gateways.