ATC Communications is one of the most requested and sought lessons for most students. Our instructors have tried most of the communication softwares out there and most leave much to be desired. One of the best ways to learn ATC Communications is simply to listen to a live ATC feed online. Try to understand what they are saying... you can listen to Class D Airports to learn class D communications, class B Airports for class B communications and so on... Once you understand the basics and the theory behind communications, practice will make perfect. Remember, even the worlds most experienced pilot and controller had to start somewhere. As always, please contact your instructor if you have any additional questions. 

Some great websites for listening to ATC.
http://www.liveatc.net
http://www.airtrafficatlanta.com/index.php