router firewall configuration

Hi there, i have the following situation.

sbs 2003 server
2 nics
zyxel 661 router
5x desktop xp

I want to connect to my network from outside the office.

I need to configure the firewall of my router but i dont know how to do this.

the server is on ip adress 192.168.16.2
my external ip adress starts 92.****
router is on ip adress 192.168.1.1

If i type in the ip 92*** internally it will redirect me to the router, if type this ip adres on a computer outside the network it will not load anything.

i set up the nat to open prts to the server.

but i also need to set up prt in the firewall but i have no idea what to refer to what… wan to lan and then which ip adres to another ip adress.

thanks already.