Let me step back a bit and say, this is not Kentico related at all but more of a standard ASP.NET question, correct? If so you may have better luck getting what you need off of the Stackoverflow website or asp.net website.
So say you have 3 projects you're working on:
1) Kentico website.
2) Standard asp.net website.
3) Website where you're building your user controls.
I'm assuming you know that your user control has to be generic enough to not have any dependencies on other projects if you plan to use it across different asp.net based websites (Kentico, DNN, standard, etc).
What I was saying in my initial post is Kentico has a web part already created that will do all the dynamic work for you. You simply copy your generic user control you created (#3) and place it in the Kentico file system (#1) and place the User Control webpart on a page within the content tree. In the webpart you set the location to that user control, which is typically something like /TheSiteCodeName/controls/usercontrol.ascx or wherever you copied that user control and click save. That's it.
In a standard asp.net website (#2) you will have to copy the user control to the websites file system and in Visual Studio you can click and drag the user control to the design part of the page and it will create a reference for you.
http://msdn.microsoft.com/en-us/library/5d0t5fak(v=vs.100).aspxI'd suggest taking a look at the examples for dynamically adding user controls to pages if you don't want to use the drag and drop method.
http://msdn.microsoft.com/en-us/library/c0az2h86(v=vs.100).aspxhttp://stackoverflow.com/questions/4302130/loading-user-controls-dynamically