RedHat should have detected it. Try kudzu from cli (not with x running) and see it it detects it. If not you will have to identify the NIC and try insmod ing the correct module for it, unless it's the same module as your first NIC.
A google search for Linux and the manufacturer or model will usually turn up the correct module for it. Or search the bbs es for hardware references. I can't think of any of the hardware references location at the moment, and don't have any bookmarked (/my bad)
I don't know how to identify the I/O and / or IRQ until you have the module loaded, and by then you normally wouldn't care because it's working. I thought kudzu and pnpisa would take care of that for you...
man modules & modules.conf for the details