Obtain a wireless adapter for each computer. Laptops will often have an adapter built-in, but desktops usually need to have an adapter installed. Internal PCI adapters or USB adapters are readily available to make a desktop wireless, and for laptops, wireless adapters are available in the PC Card format. Most laptops can use USB adapters as well.
Purchase a wireless router for the network if desired. While it is possible to network the computers without a router, the router simplifies the setup of the wireless network, extends the distance that is possible between the computers and also offers more options for tweaking and controlling the network.
Install the wireless adapters according to the instructions included with the devices. Configure each adapter to use the same SSID network name, wireless channel and password or key for wireless encryption. If there is no router involved in the network, set each adapter to use the “ad hoc” operating mode. If a router is to be used, set each adapter to “infrastructure” mode.
Configure the router if one is used. Connect one computer to the router using an Ethernet cable. Following the specific instruction in the router’s manual, go to the router’s web-based control page. This is done by entering something similar to “http://192.168.1.1” into a web browser, replacing the numbers with the unit’s default IP address. Enter the default username and password, also found in the manual. Configure the router to use the same SSID, channel and encryption password or key as the wireless adapters. The router can also be used to assign static IP addresses, set up a firewall and is capable of many other features. After the router is configured, the Ethernet cable from the computer to the router is no longer needed, and the computers should be able to connect to the router wirelessly. Connect the router to the Internet modem through the WAN port.
Set the two computers to use file and printer sharing if desired. Both computers must use the same workgroup name in order to transfer files wirelessly. If using an ad hoc network, Internet connection sharing must also be enabled for both computers to share the Internet connection. When a router is included in the network, the router handles Internet connection sharing.
Verify that both computers can access the Internet, and transfer files back and forth if file sharing has been enabled.