Using FB credentials to login to cordova app

Using FB credentials to login to cordova app

Hi,
I have made a mobile app using cordova and jQuery Mobile. Everything was going OK so far and i had no problems using any of the cordova plugins. But now i wanted to add authentication based on FB account so that users can be verified before they login the app and use server side APIs.
The problem is i can not understand how to use FB cordova plug-in. It's very confusing for me. And i havent been able to find a good titorial or help online.
The plug-in i want to use is https://github.com/Wizcorp/phonegap-facebook-plugin.
In the instructions i get confused. If i am using cordova which is supposed to be platform independent why does the page have separate installation guides for Android and iOS. And normally the plugins are fairly simple i just download them and use them after building the project. The fb plugin files are huge like a project in themselves and i don't know what to do with them.
Then i do not know how to configure my facebook app. I created a fb app but i don't know what to write in Site URL or etc

Any help in this regard will be greatly appreciated.