I used the reference you mention when I started creating user controls. You write the code in Visual Studio and then you build your solution. If everything compiles, you move the dll file to the bin directory of your Umbraco site and the .ascx file to the usercontrols folder.
Perhaps you could be more specific? Is it developing user controls in general or how to implement them in an umbraco environment that you are having trouble with?
Web Developer at Kärnhuset -
http://www.karnhuset.net - Stockholm, Sweden