Try the following steps to invite others to your iCloud calendar.
Open the Apple calendar app and tap Calendars on the bottom bar.
You should find an Exclamation mark in red next to a calendar name, click on the exclamation mark to show options for the calendar so then you should see Add person...in blue.
Click the Add person and put your friend's or spouse's email address onto the field and save it.
So then your friend or spouse should get an invitation email and when they accept the invitation, the calendar will be shared and show up on their AwesomeCalendar.
For more details on how to share iCloud calendar with others, click the below link.
If you have Google calendar, try to check below link.
If you use another one such as Yahoo or Exchange, please try to look for the instruction about inviting other to the calendar by googling. You would be able to find the information very easily.