You have to setup the Service Modes (ie: Mode 1 is "Night Service"), and Mode Times. You will also have to setup Control Sets, Ringing Service, Restriction Service, and Routing Service -- as needed.
You also have the option of setting the Service Mode for OFF, AUTO, or MANUAL. The AUTO setting uses the system clock to change the service automatically. MANUAL requires a button programmed for changing the setting on or off (Feature 871). And OFF means the mode is not in use. Let me know if you need more help.