If you are close to an airport, you can hear the ATC and the pilots. On the 'tune-in' radio app for the Roku box and iPod, you can tune in to frequencies for major (SFO, DCA, MIA, JFK, etc.) and local airports. Reading the Sectional Legend can greatly aid you in finding ...
You can find the correct frequencies on your sectional chart. When changing frequencies on the communication radio it is courteous to listen for the better part of a minute to make sure no stations are in the middle of an exchange. Only when you are sure there are no "conversations" ...
Alternatively, your instructor will show you how to set up the VOR instruments and provide you with the required VOR frequencies. Practice setting up your local airport VOR frequency while you're on the ground. Some day it might be handy when you have to return to your airport after takeoff...