You need a transmitter with a module in the back. The module is synthisized and you can change frequences by turning the dial. Something like the Futaba 8U or 9C. That would be similiar to what the instructor has.
http://www3.towerhobbies.com/cgi-bin...?&I=LXHKB1&P=0

Now consider why you want this. A nice computer radio has model memory so that all your settings and trims are saved. You just need to have all your planes on the same channel.
http://www3.towerhobbies.com/cgi-bin...I=LXGAE9**&P=0

Unless you are going to be flying your buddie's planes with your transmitter, do you really need a radio like the instructor? He has it for the ease of use with a buddy box.

As a beginner the last thing you want to do is leave it on a strange channel and accidently shoot someone's plane down when you turn on.