The ability to share your PC’s wired Internet connection to wireless devices is integrated into Windows 7’s networking interface through something called an ad-hoc network. An ad-hoc network is really just a simple, direct network connection between devices. In this case, you’ll be creating an ad-hoc network between your PC’s wireless connection and any wireless devices you want to connect. You just need to make sure that your wired connection is set up and that the PC does have Wi-Fi available.
Note that when you set up an ad-hoc network using your PC’s Wi-Fi, it will disable any existing connection that uses that Wi-Fi adapter. That’s why this method only works if your internet is coming from an Ethernet source.
Open the Manage Wireless Networks window (you can find it by opening start and searching for “wireless”), click the Add button, and then click “Create an ad hoc network”. Enter a name and passphrase for the network and it’ll appear in the list of wireless networks. Select it and your laptop will disconnect from its current Wi-Fi network and start hosting an ad-hoc network your other devices can connect to.
Be sure to enable the “Allow other network users to connect through this computer’s Internet connection” checkbox so that your PC will share its wired Internet connection with the devices connected to your PC over the ad-hoc network.