And you do it in your router via the router management page in your browser.
I've been hearing a lot of people talking about how port forwarding can greatly reduce the amount of lag you experience whether for online gaming. I have a lot people using my internet at home (8 devices on average). So how would port-forwarding help my situation?
is statically setting the router up so that data coming in on a certain port is forced to go to a certain computer.
Generally it is something like tcp on port 12657 to IP 192.168.1.4
Certain apps, and especially online games will require you to port forward to work correctly, however be aware that it stops access to that port on all other connections only the designated computer will get that data. IE if you forward the ports for an XBOX to your Xbox your brothers XBOX is now dead in the water.
Most routers support port triggering in which the computer makes a connection on that port and the router remembers it for a period of time and takes care of it for you, older routers were awful at this and port forwarding or DMZ was your only option.
In case this is about the XBOX issue with improved security, to my knowledge you either have to map out the ports in the range to the number of xboxes ie port 1 to xbox 1, port 2 to xbox 2 and get real lucky, or you have to have separate public IP's for each device, which your ISP may or may not support.