Web Server, Airport Extreme & Express

[fmp3]

I have a desktop G4 that I want to use as a web server. It is hard wired with an ethernet cable to a Airport Express. The Airport Express gets its' signal from an Airport Extreme hooked to Cox Cable broadband router. Can someone please teach me how to "clear the path" from the internet to my G4 desktop? I have not done much with port mapping, but I am ready to give it a try. I really need to know if this configuration will work or if I need to change the config. The G4 does not have an airport card but I have 3 other iBooks that do...which is why I have the wireless network.