Express Lane is one of the newest Drupal e-commerce platforms. It provides streamlined integration for PayPal Express Checkout. It's intended for easy configuration, yet it's powerful enough to use as the e-commerce or e-fundraising platform that will grow with your organization.

Download Paypal Webform Module
Download Webform Module
and enable

Go into config of Webform (from the modules screen) and select the Content Type that you want the Paypal button to appear under

Create content for that content type, save and go back into Webform tab
Create a field, using Paypal button

To get the Button ID, log into Paypal