Before You Begin
1. Try It: Log into Office 365
Go to the Office 365 portal:
https://portal.microsoftonline.com.
Please log in.

By default, Microsoft Office 365 may open to the Inbox. Look at the top of the screen on the Home Ribbon for the Calendar.

Now, Try This: Find the Calendar
Go to the Home Ribbon.
Select the Calendar.

So far, so good...

Home->Calendar