First of all, it might freeze when you select the Serial option. It happened me when I was playing on my old PC. The only setting you need there is the Internet TCP/IP option. Then, show games, and it will give you a window to type in the host PC's name or it's IP. I prefer to write in the IP, because it's the most direct option. The other PC need to have a game hosted. If it is, then you have a straight run.
However, you may also try to download the version 1.0c from the
AoK Heaven, it has a much more stabil multiplayer.