Ok, so you have the PayPal eCommerce Toolkit.
In the download center for the PayPal eCommerce Toolkit is a download for the PayPal eCommerce Toolkit Recipes. Install this MXP. Once installed, you can access the recipes from the help menu.
there is a newer extension for Paypal buttons:
payment-buttons-for-paypal/
this one allows you to edit the button from the properties screen, the eCommerce toolkit does not.