The documentation here assumed that you have successfully setup your PC to dial to your ISP. The information here is to explain how to setup a simple TCP/IP network between your PCs.
 
PC which is already setup to dial to your ISP have 2 network components installed:
  • Dial-Up Adapter
  • TCP/IP
To setup an internal TCP/IP network you need to add 2 more network components which is:
  • Network adapter. The network adapter shown here is 3Com Etherlink III ISA...
  • TCP/IP -> 3Com Etherlink III ISA...
The client PCs do NOT need to install Dial-Up Adapter and TCP/IP -> Dial-Up Adapter. They only need:
  • Network adapter. The network adapter shown here is 3Com Etherlink III ISA...
  • TCP/IP -> 3Com Etherlink III ISA...
 
On the left, the TCP/IP  for Dial-Up adapter shows that IP address is assigned dynamically by ISP.

Dont change anything here. 
The TCP/IP properties shown here is for the network adapter.
128.1.1.1 is an arbitrary IP network address. You can choose other numbers.

Each PC in your internal network will have unique IP address.
For example you can have

  • 128.1.1.1 for your server
  • 128.1.1.2 for PC 1
  • 128.1.1.3 for PC 2
  • and so on.