We are going to see how to use the Facebook feature to integrate your Facebook fan page into your app with the design of your app, and with likes and comments enables from your app.
First you have to add a Facebook page in your app by clicking from "Add pages" to add it in the carrousel of your pages.
Then just enter the ID of your Facebook Fan Page in the appropriate field, for example for our Facebook Page: https://www.facebook.com/yourpage, it will be "yourpage":
Then press "ok" to import your Facebook Fan Page.
Here is the result: