Go to PAYPAL / Paypal Config on your Admin panel. If you have a standard PayPal account you can add a widget for PayPal button to checkout template and to the quote template and you only need to fill in the email field with the email address linked to your PayPal account.In case you have a Pro account (only available for USA, Canada, and Australia), you can insert the direct payment form at checkout using this widget . To do this, you will need to feel in all fields. The credentials can be found in your PayPal account going to Tools / All tools / API credentials.