To enable Two Factor Authentication on your Bulk Buy Hosting account, start by logging in at https://billing.bulkbuyhosting.com/login.php
Once you've logged in, navigate to "Account" -> "Security Settings".
Under the Two Factor Authentication heading, click the green button that says "Click here to Enable".
Click "Get Started", and then scan the QR code into your Time Based Authentication app (eg Authy, Google Authenticator, 1Password, etc).
Type in the code that you receive on your authenticator app to confirm that they are in sync, and then store the backup code provided in a safe location.
You'll now need to use the 2FA code whenever you login to your account.