I'm not sure what you mean by that. You create an alarm with a specific time, and a function that is executed when the alarm times out,
Alarm.alarmRepeat(17,45,10,onAlarm); // Execute onAlarm at 5:45pm every day
Alarm.alarmRepeat(18,45,10,offAlarm); // Execute offAlarm at 6:45pm every day
void loop(){}
void onAlarm(){
// do whatever you want to happen at 5:45 PM (like digitalWrite(led1, HIGH))
}
void offAlarm(){
// do whatever you want to happen at 6:45 PM (like digitalWrite(led1, LOW))
}