The Facebook Like & Share button is an additional script added to the page's content.
Be aware to add the link of your page without www.
It has to look like: https://your-facebook-fan-page-url/
2.2. Click the Get Code button to generate your like button code > open the IFrame tab and copy the code:
3. How it works?
A single click on the Like button will 'like' pieces of content on the web and share them on Facebook. This button recognises automatically the Facebook account logged in the current browser session:
If you aren't logged in Facebook, you'll see the Log in window when you click the button: