Vaadin: how to add GUI using Visual Designer in IntelliJ

I want to develop a simple Java Web Application. For this purpose I picked Vaadin framework due to its "simplicity". I got the Hello World application running and now I'd like to be able to design GUI for my application using Visual Designer. I've been googling for the last few hours but haven't found anything. Would anyone be so kind to describe step by step the process of adding GUI to my Vaadin project? I'm using Intellij 14.0.3.