The task-based help assumes that you are familiar with programming in Visual Studio .NET. By following the steps outlined in the Help, you will be able to create projects demonstrating a variety of Excel for Silverlight features and get a good sense of what Excel for Silverlight can do.
Each task-based help topic also assumes that you have created a new Silverlight project and added the appropriate directives (using C1.C1Excel; for C#; Imports C1.C1Excel for Visual Basic) to the code.