In order to connect your iPad 2 to your iPhone, you will need to have the Personal Hotspot feature setup and enabled on the iPhone device. Follow the instructions from the link below on how to enable the iPhone Personal Hotspot.

Once you have the Personal Hotspot setup and enabled, all you need to do is enable the Wifi setting on your iPad 2 device and it will see your Personal Hotspot network from the iPhone. Enter in the Wifi password to connect and you should now be able to use your iPhone internet on the iPad 2 device.