Once you have been added as a member of shared mailbox, close and then restart Outlook. The shared calendar associated with the shared mailbox is automatically added to your Calendars list.
In Outlook, go to the calendar view, and select the shared mailbox.
When you enter appointments, everyone who is a member of the shared mailbox will be able to see them.
Any member of the shared mailbox can create, view, and manage appointments on the calendar, just like they would their personal appointments. Everyone who is a member of the shared mailbox can see changes to the shared calendar.