How can I setup 2-Factor Authentication for Google Apps?

      https://www.google.com/landing/2step/

   You may also refer to the following video and website for detailed instructions:

• https://www.youtube.com/playlist?list=PLXxsn2ao7Y0n-SJXhyHkWrJvZc_7GnbmM
• http://itsc.hsu.edu.hk/documents/2-factor-authentication-for-google-app/