Instant Autodesk Revit 2013 Customization with .NET
Download pdf from here
Download bonus section from here
Additional resources:
Microsoft Visual Studio
Code convert between VBasic .NET & C#
Autodesk Training:
My first Revit plug-in overview
More code learning (from ArchSmarter):
Learn Phyton, VB.net, C# and Ruby http://archsmarter.com/learn-to-code-resources/
Getting Started with Revit Automation http://archsmarter.com/revit-automation/
And last but not least:
Nathan's Revit API Notebook