The user controls are likely the public classes. If you have used vb.net, you see some of those inside the toolbox. If you want to create your own control it you should know how to create classes and dll files beyond of this ActiveX components.
It takes time to learn but I suggest you to start with creating classes for the specific application you have worked on. The classes are much easier where you can define properties of the objects and then internally call this inside your code...
Take it easy!