Migrating your calendar data is a two-stage procedure that involves first exporting it from your previous system, and then importing it into the Cloud server.
Sign in to your Google account, and go to the Google Calendar app.
Open the Settings menu and choose Settings.
Under Import & export, choose Export.
Click the Export button to download your calendar(s).
The downloaded *.zip archive contains one or more exported calendar(s).
You’ll need to unzip the individual iCalendar (*.ics) files and import them individually.
Right-click the calendar you want to migrate and choose Export Calendar… from the pop-up menu.
Choose where to save the iCalendar (*.ics) file.
Go to File > Save Calendar.
Choose where to save the iCalendar (*.ics) file.
In the Cloud server Calendar app, click on Settings & import at the bottom-left corner of the page.
Click on Import calendar and select a local iCalendar (*.ics) file.
Choose whether you want to import this into your Personal (default) calendar, or a new calendar.
Repeat as necessary if you are importing multiple calendars.