You need to give us more information about your network.

How is it set up?
Is there a computer acting as a router, or do you have a standalone router?
What connection do you have? (Cable, DSL, etc)
How many computers are on the network?
Who set up the network?
Where can you go to forward certain ports to certain computers in your network?

I would really recommend asking the person who set the network up to do this for you. They are the ones who know the most about the network. I know some about networks in general, but it will be really hard for me to help you if I have to ask you questions and then you need to give me the answers, when you aren't really sure that they are correct.

Tell the person who set up the network that you want to forward ports 10052 to 10054 to the computer you play JJ2 on.