The clock is automatically set to your local time. To set the alarm simply enter what time you would like it to go off in 24 hour format (army time). You can convert here if you are not familiar.
For instance if you wanted to get up at 8:20am you would set it 08:20 don't forget the colon. If you wanted to set it for 8:20pm you would set it as 20:20.
After you enter the time hit the "Set Alarm" button. When you push the button you will see a green hand appear on the clock. That means the alarm is set for that time.