In order to start the program in debug mode, we choose [Debug] -> [Start Debugging] or press [F5]:
After starting the program, we can see that it stops executing at row 11, where we placed our breakpoint. The code in the current row is colored in yellow and we can run it step by step. In order to go to the next row we use the key [F10]. We can see that the code on the current row hasn't executed yet. It executes when we go on the next row:
From the Locals window we can observe the changes in the local variables. In order to open the window you must choose [Debug] -> [Windows] -> [Locals].