Create demo for C# .NET .dll for access from plain "C"

I need a .dll implemented for .NET. This .dll must be possible to use from traditional c/c++ in WIN32, and I am planning on calling it from Python (not your responsibility.) The purpose of this project is to show how a WIN32 dll can be created using Visual Studio 2010 using .net, and if possible c#. The .dll must be possible to use from a Visual Studio 2010 WIN32 console application. The interface of the dll shall have exactly one function with following type of functionity: WriteFile( string filePath, string fileContent) The Visual Studio 2010 shall contain both projects. THE DLL MUST USE .NET APIs and PREFERRABLE USE c# as language