Extend Sitefinity CMS data model: Create the class library
 You first create a new class library, in which you implement your custom logic. Thus, you can easily reference this logic in your project and use it directly in your web application. To create a class library for extending the Sitefinity CMS model, perform the following:
  - In Visual Studio, create a new project.
  - From the main menu, navigate to File » Add » New Project.
  - Click Visual C# » Windows » Class Library.
  - Name the project CustomTypes and click Add.
    A project with a single class file is generated in the solution.  - Delete the Class1.cs file from the CustomTypes project.