This video will show you how to put your iDevice into DFU mode.
1. Power off your iDevice, Plug it into the computer and follow the steps below to put your iDevice in DFU mode. The steps are as follows:
I. Hold down the power button for 3 seconds
II. Continue holding the power button and start holding the home button and continue HOLDING BOTH for 10 seconds
III. Let go of power and continue holding home button for 20 seconds (or until iTunes pops up on your computer).
2. If you followed the steps correctly, your iDevice should now be in DFU mode.