Use the Calendar feature of Outlook WebApp (Office 365 for students and off-site version for Staff/Faculty) to set an appointment (group meeting, test, campus event) and also set a reminder for it.  Sign in to your Outlook Web App account and follow these steps:

1. Click Calendar (lower left).
2. Make sure Month view is selected (next to the word Share).
3. Move cursor to the date of the event – Double-click to add an event.  will appear.
4. Double-click; Untitled Appointment window will open.
5. On the Appointment tab, complete the information about the event.
6. Make sure the box in front of Reminder in the area just above the formatting toolbar has a check mark in it; if not, click inside the box.
7. Use the drop down arrow to set the time before the scheduled event for the reminder to appear.
8. Use the message body for any other additional information about the appointment.
9. Click Save and Close.

A text box will appear on the calendar with some information about the Appointment.
Move the mouse over the text box to see more information.

A pop-up reminder should appear about the event at the time specified – if you are logged into Outlook at the time.