I bought a used radio for my 2003 silhouette I need to unlock the radio I need the proper procedures to unlock it.

You definately have a problem. In order to unlock the radio you will need the VIN of the vehicle that you got it from. You will also need proof of where you purchaced it from. Take all this information to a GM dealer and they should be able to unlock the radio by entering an "Override" code to unlock the radio. Then they will have to program your Engine Control Module to accept the "Brodcast ID" of the replacement radio. This is all part of the antitheft system designed to keep someone from stealing your radio and using it in another car. If you can't get the VIN of the vehicle that it came out of, the dealer will not be able to help you because there are many different override codes and they will not know which one to use without the original VIN.