Me and my friends turned an old office computer into an ubuntu server for Minecraft, and once it was built and set up to host Minecraft, we were told to port forward it so that they could play on it, but because my router uses CG-NAT this wasn't possible. Further online searches on Spark's website said to use a static IP, so I've purchased one from Spark. However now I'm completely lost on how to go forward, i.e. forwarding the port so that my mates can actually connect to it.
Any amount of help / advice would be greatly appreciated as there isn't really any info online and I'm a complete newbie when it comes to anything network related.