If you created a Yourdrive account by connecting to Facebook, you weren't required to create a password.
You can continue to log in via Facebook, or if you'd like to have a different Yourdrive account password you can create one by logging out of your Yourdrive account and then following the instructions on our 'How do I reset my password?' FAQ.
Once you change your password, you'll no longer be able to sign in using Facebook.