Share your own Calendar

From Microsoft Outlook:

Select Calendar (from the icons down the left side)
Click Share Calendar (from the options at the top, also known as the “Ribbon”)
Choose a calendar to share.
Select Add, decide who to share your calendar with, and select Add.
Select OK and you’ll see the added people with a default permission level.
Choose a name, select the access level to give, and select OK

for more information, please check this Microsoft Article