To set up an additional security layer on your account:
VIsit Your Profile Page and follow the prompts in the "Advanced Security Settings (2FA)"
Download an Authenticator App onto your phone (like Google Authenticator or Authy)
Add a new account (on your Authenticator App)
Scan the QR Code (or enter the 16 digit key if setting up on mobile)
Go back to Stake and enter the code generated on your app.
Boom. That's it.