Code execution continues until you reach the breakpoint. You have reached the breakpoint when it turns a lighter color of red. After you reach the breakpoint you can watch variables by double clicking under the Name column and entering a variable name. Notice also that output is displayed in the console window.
You can step into functions by clicking on the Step into icon
You can step over function by clicking on the Step over icon
You can continue to the next breakpoint or to the end of the script by
clicking on the run Icon. 
You can break out of the debugger by clicking on the reset button.
