Laptops almost always come with a pre-installed wireless Internet card. To connect a laptop to a wireless access point, either set up a home router and connect to that or visit an establishment that offers public wireless Internet.
A router, which is required to connect to a home wireless network, can be purchased at any electronics store. Once the router is physically set up, open the laptop's networking utility (e.g. the Network and Sharing Center in Windows 7), and connect to the network marked with the SSID of the router. Most laptops have a hardware wireless network switch, which is usually marked with a tower and waves. If this switch is turned off, the laptop cannot connect to a wireless access point.