1. Visit https://outlook.office365.com/calendar/ExampleCalendar@lyndendoor.com, make sure to replace ExampleCalendar.lyndendoor.com address with the calendar you want to edit.
2. Click the Share button in the top right corner.
3. Enter the email address of the person with whom you're sharing the calendar with.
4. Provide the desired permission level and then click Share button.