In order to keep up with appointments, you should be reminded of those events well in advance. Zoho Calendar enables you to receive reminder notifications as email, as pop-ups or even both, for every event.
Click on the event you want to set reminders for. This will bring up the event edit dialog box. Select "Edit" option from it.
In "Remind me" section, click on "Add reminder" link.
Choose the time and mode of reminder from the drop down box.
For multiple reminders, repeat steps 2 and 3. Click on "Save" button to update the changes.