This seems like a daunting task for new users, but it's really not all that bad. There is a section in the IPNR manual beginning on page 21 about how to configure a setup like we propose. We'll condense things here, but we also must explain a little more than you probably want to know about IP addresses. There are several kinds of IP addresses for different uses. In this case, we want to define two different types of addresses, internal and external.
External addresses are the ones used on the Internet.
192.168.X.Y. An IP address of the form 192.168.X.Y will be used for your Apple II GS once we're done. You'll need to also select an IP address. Well, for your router, you will probably want to select an address like 192.168.0.1. The IPNR manual suggests not choosing this particular address as it is very common and may conflict with other users on your cable modem service and suggests a number such as 192.168.73.1. Then, when you want to use IPNR, you'll just need to double click the configuration file.