This documentation is in progress as of March 8th, 2013. We are working on big improvements for the coming weeks.
Click here to see a step by step tutorial on how to build a Windows Store (Windows 8) app using the Facebook C# SDK.
Sample for Windows Store Applications can be found at https://github.com/facebook-csharp-sdk/facebook-windows8-sample. The sample contains a sample project as well as the source for the tutorial above.