C# using System.Windows.Forms does not exist

Question

I tried to add:

using System.Windows.Forms 

But its shows me an error.

I know I must assembly that to my VS2012 but I srsly don't know how. I was searching everywhere and tried everything I've found but none of this helps me.

@edit 1 hour of searching in the web and... 2 minutes after write this post i found... Project >> add Reference...

Solved :]

Answer 1

If you're using Visual Studio, right click the References folder in your project, select Add Reference... and then on the .NET tab, choose System.Windows.Forms and click OK.