Amazing ClassiCube fanfiction. I am a book publisher and would like to see it become a bestseller recommended by The New York Times. Would you like to accept my offer?
what router do you have?
also port forwarding is easier on Linux (if your on windows, good luck: I have no clue on how to setup port forwarding on windows)
In addition to Panda's video, would recommend to check out this tutorial which shows the process of whitelisting a TCP port in Windows Firewall. Disabling it entirely makes your PC vulnerable to a few attack vectors.
There are other server softwares, however, MCGalaxy is the most used one, and is typically up to date with the client, as they are made by the same developer.