Thanks for writing.
After you have downloaded the MSI installer you can install it on your machine and then run (restart) Visual Studio. Please, refer to the following article
for more information about how to set up a new RadControls for ASP.NET project.
Another resource I would recommend is our Step by Step tutorial. It could be downloaded from here
Let me know if you have any further questions.
the Telerik team
If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed