How do you connect my iPad to the internet using my iPhone?

Tap Settings from home screen, select Wi-Fi then turn Wi-Fi ON by tapping over the OFF button right to Wi-Fi.

Now after a few seconds tap on your Wireless name (SSID configured on your W/L router/Access point) from Choose a Network lists

then enter the Preshared key on prompt.

If the key you enter is correct then you are connected now.