Add to Chrome.
Click 'Add extension' above.
The installation process should take less than a minute.
Next, you'll Create an Account.
My Yubikey is not lighting up when I push it. What do I do?
Test your Yubikey here -- http://demo.yubico.com/
If it is failing, then you will need to contact Yubikey directly on a replacement - http://www.yubico.com/faq/my-yubikey-is-not-working-what-should-i-do/