To set an alarm for a Calendar entry:
You can also set an alarm while adding an entry by
tapping the Alarm button on the panel and selecting the
Alarm option.
Entries which have alarms are marked with a bell symbol. To remove an alarm, tap and hold the stylus against the screen at the entry whose alarm you wish to deactivate. Select the Alarm tab from the Calendar: Edit event dialog box and toggle the Alarm button off to deactivate the alarm.
At the pre-determined time, the Alarm will sound and you can mute, dismiss or set the Alarm on snooze.