To connect to Wi-Fi, open the list of available connections from the Network menu on the computer, select the wireless connection and enter the security key if needed. The computer also needs to be close enough to the router to pick up a strong, reliable signal.
On Windows, access the list of networks by clicking the wireless icon in the system tray. A list of wireless networks appears with different numbers of bars marking their respective connection strengths. Highlight the relevant connection, select it and click "Connect." Enter the security key when prompted. Be careful about connecting to unsecured networks, which are marked by a yellow shield because anyone can access these networks and potentially intercept data.