Request time off approval
In step 2 you discovered how to add time off to your calendar.
If you want someone to approve a time off (like your boss, project manager) all you should do is to add that person's name to the approval box, while adding and event.
While adding an approver you can also submit a private note. All approvers will receive a private note, but nobody except them is able to see it.
All the approvers will receive an email notification. Once the request is accepted by all of approvers - it's added to the calendar.
If your request is rejected by at least one approver - you won't be able to see it on your calendar grid.