1) Sign in with your existing PayPal account or create a new one.
2) Enter your shipping, payment and contact information, or use the one stored with your existing PayPal account.
3) When done, click "Continue" button to confirm your payment.
Finally, you will be redirected back to the store checkout page. Review your order details and click "Submit order" button at the bottom of the store checkout page to confirm your order.
Note: If you are not automatically redirected from PayPal back to the store checkout page, make sure you click "Return to merchant site" button at PayPal side.