1. Once a breakpoint is hit you can
2. Step through your code
3. Step into functions
4. Step over functions
5. Step out of functions
6. Continue execution after breakpoint
7. Evaluate variables or expressions on the fly by moving your mouse over them
8. Add variables or expressions into Watch to monitor the change
9. Stop debugging

Evaluating of variables and expressions:

1. Once a breakpoint is hit
2. Move your mouse over a variable in the code that has been already executed (above the breakpoint)
3. The debugger will evaluate the variable and show it's value as a hint:
   
    
4. To evaluate an expression simply select is and move your mouse over the selection:
   
    
5. In order to add a watch, simply select an expression, right click and select Add Watch:
   
   
   The watch value will be available only after you step.
   
   Note: Expressions added in the watch require the debugger to reevaluate them on every step, which usually slows down a bit every step. That's why most of the clients, including myself, prefer evaluating the variables on the fly through a hint.