Assuming you are using Windows XP and you want to share a network connection through your main computer you can activate Internet Network Sharing on your computers.
NOTE: This is NOT the best way to set up Internet access on serveral computers. But is designed to SHARE one connection.
Internet Connection Sharing overview..With Internet Connection Sharing (ICS), you can connect computers on your home or small office network to the Internet using just one connection.... When you are setting up a home or small office network, it is recommended that you use the Network Setup Wizard in Windows XP to enable Internet Connection Sharing. The Network Setup Wizard automatically provides all of the network settings you need to share one Internet connection with all the computers in your network.
Note: To start the Network Setup Wizard, click Start, click Control Panel, and then double-click Network Setup Wizard.
After ICS is enabled, and you make sure that all of your computers can communicate with each other and they have Internet access, you can use programs such as Internet Explorer and Outlook Express as if they were directly connected to the Internet service provider (ISP).
When a request to the Internet is made, the ICS host computer connects to the ISP and creates the connection so that other computers can reach a specified Web address or download e-mail.
To test your network and Internet connection, see if you can share files between computers and that each computer can get to a Web address. For details open Windows help and support and search for Internet connection sharing.
FYI... If you have a dial-in connection this is active only if you are using the telephone modem in the computer and it is NOT good for sharing...
A local area connection is an Internet connection to the Broadband network... It is normally connected by an Ethernet Cable from the computer to a networking device that is then connected to the Internet. You say that you don't have a modem, but there HAS to be some networking device the Ethernet cable from your computer is connecting to. It normally is a Cable or DSL modem, or a router, however in some cases it can be directly to a special telephone line like a T-1.
It can also be a satellite connection, or a wireless Internet connection through a Cellular Telephone Network.
The best way to setup a network is to find the networking device Cable/DSL modem and connect a router to it then from the router to each computer. This way each computer is connecting to the Internet and not one computer connecting through another computer.