To import events and tasks:
In two-pane layout, click the Import/Export icon from the calendar quick actions menu.
In three-pane layout, select the Import/Export option from the Actions drop-down list on the calendar toolbar.
Select Import.
The Import Events and Tasks window appears.
In the Select File section, click Browse.
Select the file you want to import by navigating through the file system.
Select the calendar into which you want to import the events from the Calendar folder selector widget.
Click OK.
When the process is complete, a message box indicating that the import has succeeded appears. If an error occurs while reading the imported file, an appropriate message appears and you will be prompted to try the import operation again.