C# – ASP NET C# System.Windows.Form does not exist in the class or namespace ‘System’

asp.netc++visual-studio

ASP NET C# using System.Windows.Form namespace producce error "The type or namespace name 'Windows' does not exist in the class or namespace 'System' (are you missing an assembly reference?)".

I test it with WinXP ver 2002 SP3,
MS Visual Studio Microsoft Development Enviroment 2002 ver 7, framework 2.0;
and with
Win7Professional, MS Visual Studio 2008 Express, framework 3.5 (inside Win7?)

Best Solution

Add a reference to System.Windows.Forms in the visual studio by right-clicking the references or project in the solution explorer.

But I could not figure out what it has got to do with ASP.NET?