From the menu, create a new Silverlight application
Make sure WCF RIA Services is enabled.
The result is a new project divided into two parts as can be
seen in the Solution Explorer.
A first part called ObservableCollection and a second with
the same name but with the extension .Web.
The first part can be seen as the Silverlight part running
on your computer. The second one runs on the Internet. Communication between
these two parts is done using WCF RIA Services.