Step 1: Click on the Calendar button in Outlook



Step 2: Click on your 'Profile Picture' in the top left


    

Step 3: Click on the 'Settings' Gear Icon next to the calendar you wish to share (NOTE: You can only share calendars that belong to you!)



Step 4: Click on 'Add People'



Step 5: Search for the user you wish to share your calendar with or enter an email address



Step 6: Click on the user you just added



Step 7: Select the Permission you wish to give along with what they are allowed to see (NOTE: This can be changed later)



Step 8: You should now see all the users that have access to your calendar. Here you can change permissions or remove users.