In C#, you don't import a class, but a namespace. For instance, class may be defined as:
namespace Ui.GlassControls
{
public class UIGlassButton
{
.... // methods, properties, whatever
}
}
In the source file that requires the button, you would use:
using Ui.GlassControls; // namespace reference
....
// inside of some class
UIGlassButton ugb = new UIGlassButton();
// or
Ui.GlassControls.UIGlassButton ugb = new Ui.GlassControls.UIGlassButton();
the second instantiation method bypasses the need for a "using" statement, since it refers to the control by its fully qualified namepspace.controlName identifier.
Note I'm not familiar with UIGlassButton specifically, so you'll have to search to figure out what assembly it's defined in, and what file you need to reference from the calling project.