ICS or Internet Connection Sharing is a tool used in Windows to share your internet conection be it Wifi or Lan.   To set up the conection you will need the following:

Ethernet Cord
Laptop or Desktop running Windows 7
Administrative Rights on that computer

Now for the steps.

1. Open Network and Sharing center
           To do this open your start menu and search Network and Sharing
2. Click Wireless Network Connection (Your Router Name Here)
3. When the dialog box opens click Properties
4. Then in the sub-menu click the tab Sharing
5. Check the box that says (Allow other Network users to connect to this computer's Internet connection.
6. Press OK and close all open windows.
7. If you are using a laptop make sure it is plugged in then plug the Ethernet cable into the slot on you computer.
8. Turn the other computer on and there you go.

Note- This also allows you to connect your Xbox 360 or any other device with an Ethernet Connection slot to the Internet.   Also please make sure you disable your Windows Firewall I always seem to have a connection problem when it is enabled because it tries to block the other devices.