Joseph is right, the sample site can be explored from the project manager. You'll notice a link below the grid with projects that says "Explore sample site". By clicking on that link you will create the sample site and will be able experiment with it.
In addition, you are also right about our documentation. I've just checked the pages about sample sites in our User Manual, and honestly, we don't explain that very well. I've already notified the people working on User Manual about this.
Thank you for bringing this issue up. Your feedback is very much appreciated.
the Telerik team