Follow the normal checkout steps using PayPal as your means of payment, after the final confirmation screen you will be greeted with a PayPal Login Screen (below), now follow the below screen shots.

Now, you are presented with a form that requires the information about your credit or debit card. Depending on your country, you may also be asked to enter your address, email address, or phone number. To continue after entering all the information necessary, simply click on “Pay” at the bottom of the form.