Hi @YouliTang,
Unfortunately, I don't know of a any great way to import calendar items. The Items would come over from a prior course if you do a course import/copy, but if you're entering items for the first time I think you will need to do do it one by one right in the calendar. If you're a programmer or have access to programmers, there is a calendar events API that could be somewhat useful to custom code something for your needs.
-Chris
