This article has links (in blue letters) to a dozen other articles on specific internet connection subjects:
50106- How to Connect to the Internet and Set Up a Network in Mac OS 9
There are three slightly different sets of rules:
1) you are using Dial-Up:
In this case, you will enter the "magic numbers" given by your ISP, possibly including a username and password. If you need help interpreting "what goes where", lots of folks here can help.
2) You are using Broadband, but you do NOT have your own Router/Gateway:
In this case, you enter the "magic numbers" given by your ISP. If you need help interpreting "what goes where", lots of folks here can help.
3) you are using Broadband, and you have your own Router/Gateway:
In this case, you use the TCP/IP Control Panel to connect via DHCP, and the rest of the fields can be left blank.
The changes you make in TCP/IP Control panel do not go into effect until you close the Control Panel and indicate that you do indeed want to save the changes.