Hello @textbook_quest Analogue clocks are a bit tricky at the beginning but no worries, thanks for asking this question! 
At the back of your Mudita Bell there are two knobs - the small one is for time, you can set up hour and minutes. The bigger knob with orange dot is for alarm. Remember to rotate accordingly to the indicators. The alarm has only one, orange arm on the clock dial. If you want to set an alarm at 8:00 you just simply put it at 8. If you want your alarm to go off at 8:30, you have to set the orange arm in the middle between 8 and 9 on the clock. Remember that since it is an analogue mechanism, the alarm might go off up to few minutes before or after. It is not as accurate as electronic clocks such as Mudita Harmony.
Once you set the alarm make sure you activate it - deep press the main knob at the top so that the orange strap is visible. You can also double check if the battery is charged for sure. If you think there might be some issues with the device you can always reach out at support@mudita.com
Ula also wrote a few words at the end of this thread, you can check it out there too - Introducing Mudita Bell & Mudita Harmony!
Hope it helps! 