ChatHub and OWIN Startup Class Not Found in VS 2013

Hi.... I am working on a DNN7.2 based on project ... and try to make a chat module .... i am working with vs2013 but my project is on 4.0 net framework so i install SignalR via NuGet by console. I use the help from this link.... 
http://www.asp.net/signalr/overview/signalr-1x/getting-started-with-aspnet-signalr/tutorial-getting-started-with-signalr
but when i want to add new class , i don't know where i add this class in my dnn7.2 project, 
                                      
In Solution Explorer, right-click the project, select Add | Class. Name the new class ChatHub.
In Solution Explorer expand the Script ...