A reader had a question about adding a reminder to Windows 10 calendar events:
“Can you set one or more pop-up or e-mail reminders in advance of the appointment?”
Click the date and time at the bottom right of the screen.

The calendar will pop up.

Click on any date.

A box will appear at the bottom. Just start typing the name of your event.

Once you type the event, you’ll see options to select the time.

Click on the time to set.

Then select the time from the pop-up menu.

You can also add a location.

If you have more than one calendar, click at the left for a drop-down menu.
Choose the calendar you prefer.

Click on More Details.

The default time set for reminders is 15 minutes.

Click the drop-down arrow next to the time.

Then choose Save.

A reminder pops up at the time you’ve selected.

It also popped up in my inbox for Outlook online.
