Make sure the Arduino is still connected to your PC via USB. If you run the application now (by pressing F5), it will communicate with the Arduino, and display any values read to the event log. In the GitHub project, I've added a couple of GUI components to our main window, that display the most recently read pin values on it. It also displays any event messages logged. We leave the relay for later chapters.
For a more generic example, see the Waher.Service.GPIO project at https://github.com/PeterWaher/IoTGateway/tree/master/Services/Waher.Service.GPIO. This project allows the user to read and control all pins on the Arduino, as well as the GPIO pins available on the Raspberry Pi directly.