Connect one end of the USB cable into your computer, but leave the other end disconnected from your iPad. Press and hold BOTH the Home AND Sleep/Wake button for about 10 seconds. When the screen goes black, let go of the Sleep/Wake button but keep holding down the Home button. While continuing to hold the Home button, connect the iPad to the USB cable. Wait a few seconds. When you see the Connect to iTunes screen on your iPad, let go of the Home button.
You can then use iTunes on your computer to restore the iPad.
Hope this answers your question!