You have to use the email text version or URL of the item button code. Once you create the link, just copy and paste it into your Facebook post.
Assuming you have a Business account. (Personal accounts do not this option.)
* Login to your account.
* Select on Tools.
* Click on All Tools.
* Click on PayPal Buttons.
* Choose the Button type you want to make.
* For example: Buy Now.
* Click on Select Button.
* Enter the info you need.
* In step 2 you have the option to save the code at PayPal or not.
* When finished with all the details.
* Click Create Button.
* On the next screen you will see the generated code.
* Click on the Email tab - that will display the code you need.
* Click on Select Code - then copy and paste the code in your email or document.
* Done.
Note, the "Email" tab will not be available if have included dropdown selections or text boxes in your item button code. This is because you cannot include dropdown selections or text boxes in a Text or Hyperlink.
