Johnny
Unplug it, throw it in the washer, then in the dryer, then back in the washer, run over it, go "office space" on it, burn it, then by a mac.
Or if you go to the bottom left of the screen there should be an option to shut it down. There's also a button like that to the right of the screen. Also on any Windows Computer look for a power button. Either on the front of the computer tower (desktop), or on the top of the keyboard (laptop).
Anonymous
Look on the start menu find power then select shutdown
Scott
Most people use either the power button, or select "Shut down".
Chas
The same way you turned it on.....