Once you're ready for checkout, go ahead and click the "PayPal Check Out" option
You will need to login into your PayPal account. If you do not have one, you may go ahead and "Create an Account".
Once you have successfully logged in, you will need to be approved by PayPal. Click "Apply Now" and fill out all the necessary information. If you have already gone through this process, you may skip this step.
Once approved for the new PayPal Credit option, go ahead to the "Pay With" section and click "Change". Your new option for PayPal credit will now be available for you to use. Checkout normally from here and you're done!