Can someone help me out here?

Ok, I have a router and i want to host games for ESF, CS, NS, etc... my friend has a router and he can host servers with no problem, can someone try and explain or tell me how i can host a server with a router where people can join and not get kicked out in like 2mins of playing? ;/ :S

We'll heres how it works for my Router...( me thinks )
First you have to log into the router... ( simple by typing in the IP...)
Then you your Computer to be the Dmz host.
There can only be one Dmz host per router I believe.
Thats how it is with mine.

Ok I'll try that thnx, hopefully it works