Help: .NET controls dimmed on Toolbox

[VB Programmer]

I downloaded some pure .NET, managed, custom controls from a website. In
VB.NET I can add them to the toolbox fine, use them, etc... But in a webform
when I add it to the toolbox it is DIMMED and I can't use it.

Because it's a fully, managed, pure .NET control, doesn't that mean I use it
either in a winform OR a webform?

How can I use it in a webform? Whats the easiest way?

Thanks.