When you are finished using the computers, you should make sure you have saved all your work to a USB drive or to your H Drive and then logoff or restart the computer to protect your privacy.
Click on the Start button (round windows icon on the bottom left of your screen).
On the bottom right of the dialog box that opens you will see a prompt to Log Off or Shutdown.
If the prompt says Log Off, click on it.
If the prompt says Shut down, click on the arrow next to it and then click on Restart or Log Off.