iPad connects to Internet via WiFi. If Wi-Fi is not available iPad (cellular models) can connect to the Internet using your carrier's cellular network. When you use an iOS app, your iPad connects to your current Wi-Fi network if accessible. For more information, visit http://support.apple.com/kb/HT1695.
If you have a Wi-if network, you can simply go to settings, then turn airplane mode off if it is on. Then simply click wi-fi and turn it on. Choose your wi-fi network, then enter the password if your network is password protected.