I'm not sure what you're asking. SmartDashboard is a Java program, designed to communicate with either a Java or C++ robot. For most use cases, it is not necessary to modify SmartDashboard, because it dynamically adapts to the data your robot is sending.
I'd recommend reading
http://wpilib.screenstepslive.com/s/3120/m/7932. While the robot examples are generally in java, the same methods exist in the C++ SmartDashboard class.