How to add these controls to my project? (C# winsforms .net 4.0)

All controls are always added this way:

class SomeControl : System.Windows.Forms.Control { // some C# Avionic Instrument Control; or any other control
    // ...
}

//...

Panel parentControl = new Panel(); // can be Form, some other control which can be a parent
SomeControl myControl = new SomeControl();
SomeControl someOtherControl = new SomeControl(); 
// set up properties, alignment and other

//...

parentControl.Controls.Add(myControl);
// alternative way, with the same effect:
someOtherControl.Parent = parentControl;

Well, the assembly (or assemblies) should be compiled and referenced. The best way of doing so it to put all source code under the same Visual Studio solution. In this case, the reference can be added by referencing the project, via the tab "Projects" of the "Add Reference" window. The reference itself is always between compiled assemblies, but in this case, it is done automatically, modifications in the project in dependencies are taken account automatically, and the dependencies between projects are detected automatically, based on those references.

For everything else, ask the author of the article, if needed. Locate the section "Comments and Discussions", hit "Add a Comment or Question" and add your questions. The author will get a notification and a chance to answer you.

However, I have a strong impression that you are going in a wrong way. The question reveals that you don't have understanding of basic development/support cycle. This is perfectly fine, it will come with time. First of all, you need to learn it all and try to develop something very simple, to get basic understanding and confidence. Instead, you want to get something "cool", fast. Well, you can, but don't forget: you should not skip those more important steps when you do everything from scratch, with full understanding of each step, based on first principles, without asking for a cookbook step-by-step recipe.

Good luck,

—SA