Extensive documentation for the .NET Framework SDK can be found at the MSDN website using the following URL: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/netstart/html/cpframeworkref_start.asp
The documentation includes tutorials, code examples, and a complete description of the contents of the .NET Framework libraries. Spend time getting familiar with the online C# documentation—it's tremendously useful!