Like 2 Show is a Joomla module intended to generate likes for a fanpage. It requires visitors to press 'Like' in order to access additional content. This is useful as a different kind of paywall to premium articles, eBooks, photos and other interesting digital content.
Use the Joomla extension manager to install mod_like2show.zip. Next, configure Like 2 Show module in modules section, all basic fields are necessary. You will need the API credentials for a facebook app to set App ID and App Secret, you can create one here. You will need also your fanpage ID and URL. Finally, set the text messages that are shown to the visitor.
Set the module to active and set the module position. You can also put module into an article, see this link for mode details.