To create a calendar, navigate to the Calendar section and select Add calendar → Create New
3 easy steps to create a calendar
Create a Calendar. Any user can create an unlimited number of calendars.
From the main menu JIRA you should go to the "Calendar" and on the right side click "Add Calendar" then chose the "Create New" link.
Customize a Calendar. Any user who has edit calendar permission can set up custom fields in calendar events and their legends. You can create calendars for different cases: planning specific project or a product, employee, group of employees or the special issue types (such as a vacation or a business trip, or marketing activities).
To tune in your calendar, you could go to the "Calendar" on the main tab, and on the right side click "Calendar's Cog" then choose "Set Up" link.