Log in to your PayPal merchant account and click on the Merchant Services tab to create a payment button for your website. Enter the optional item details, then select a button or use your own image to customize the look of your button.
Optional: Enter information about shipping, sales tax, your logo, and the page users are sent to after payment; or you can let your Buyer fill in the appropriate fields during purchase.
PayPal will generate HTML code which includes all details of your payment. Highlight and copy this unique HTML code.
Add the HTML code to your form by clicking on Add another Textarea (1), hiding the editor so that you can add code (2) and pasting the Paypal code (3)
Don't forget to save!