Once you have the link to your Facebook page, you can then add it anywhere to your email.  Keep in mind, you can also use the link as a hyperlink, button, or you can also utilize our social media buttons in our Drag and Drop Editor.  We also have an integration with facebook, to automatically post your emails to Facebook when you send.  Please see Facebook Integration.  If you are having any difficulties adding the link to your email, please contact our support team.