Be a bit more specific; what system, and where (city/state)?
The answer will depend on what kind of system you are trying to program; EDACS, Motorola (what kind?)....but in general, you need to first put the scanner into trunk programming mode then select the kind of system you are trying to program. At that point, once you've entered that information, you start entering frequencies. PP40-41 of the owner's manual tells you about this. 73s Mike