After you have downloaded your project to the target board you can run it.
If you have selected valid Loader for the project using project settings, then the Set mode toolbar button will be enabled and will indicate GREEN light.
Green light means that the program is running on the target board (RUN MODE).
RED light means that the program is not running on the target board (PROGRAM MODE).
Click the Set mode toolbar button. The button will become green and the program will start execution.
When the program is running on the board, you can see its output in terminal window. You can also send input to the program ( through the serial port ) using the Terminal Window.