Today and last week as well, in my project I had to go through the FaceBook API. The API is located here. http://developers.facebook.com/docs/reference/api/user

The API is very straight forward call to the REST service. For testing, you will need to get the token by loging in to FaceBook with your account. The token can be then used to make a REST service call.

I found the following C# API library very useful.
https://github.com/facebook/csharp-sdk

I hope this is useful.