How to correctly setup portforwarding

Dear Community,

I have installed IPFire on a desktop with 2NICs, DHCP working fine etc.
I’m investigating how to correctly port forward. I have read this:

I would have several portforwards to different hosts on my LAN as follows:

IP-fire-serverIP:8080 => 192.168.0.5
IP-fire-serverIP:8081 => 192.168.0.6
IP-fire-serverIP:8082 => 192.168.0.7
IP-fire-serverIP:8083 => 192.168.0.8

How can I get this done:

Please advise,

regards
1960web

This is done as described in the wiki article cited.
Example:
<WAN address>:8080 ( source )
192.168.0.5:<service port> ( destination )
<service port> = 80 for HTTP or what ever the webserver is listening to.