Well, let me get a few things first.
Goal Cameras are CCTV? If yes, are they hooked up to a DVR. If they are ip, are they hooked up to the network? Can you view them?
If you can't you obviously need to get them connected, if you can, continue on my friend.
In the coach's box, they need to be connected to the same network as your cameras. The wire running to the Nanostation is your POE wire, powering the Nanostation. The other wire is your LAN wire. You'll plug that into a switch so you can connect multiple devices to that nanostation. Once you can you'll just plug a computer, laptop, all in one etc and connect them to the DVR that way.
Or if you wanted to do it with a tablet, you can use the app support of your DVR to let the coaches view the entire DVR. You'll probably need to give them a seperate user and mess with those permissions so they only see what you want them to.