When Reminder starts (on every Windows boot), it shows itself as a recognizable tray icon (white letter R in a blue circle) and a Viewer form with events if there are any for that day. If tray icon flashes to red, it means that you have at least one event with an alarm to come for today, and that you haven't switched off this option in Config. Left mouse clicking on Reminder's tray icon shows Calendar, and right clicking shows menu with following options:

Calendar shows Calendar form with events

Today shows Viewer form with today's events

Settings show Config form to change settings

Register shows Registration form to enter registration unlock key

Alarms force alarms on/off

Help shows Reminder's help

About shows About form

Exit shuts down Reminder