After you've completed filling out the Main Window and clicked the Start button you will open the Sending Window.
Sending Window - Ready to Start
Just click the Start Sending button to begin your send operations. While it's running the Stop Sending button will be enabled so that you can stop your operations before they complete if you wish.
Once it has completed (or you have clicked the Stop Sending button) your results will be compiled and you can view your results.
Sending Window - Ready to Start
You can repeat your operation as many times as you like just by clicking the Start Sending button again.
Your Next Step: Review Your Send Results
