- Open the Sunbird application and select File > New Calendar.
- Select On the Network and click Next.
- Select the CalDAV format option.
- In the Location field, enter [ https://www.google.com/calendar/dav/ [ your Google Calendar ID ] /events ] and click Next.Your Google Calendar ID for your primary calendar is just your email address, but for all other calendars the Calendar ID will be in the form of [ long string of characters]@group.calendar.google.com. You can get the Calendar ID by clicking the down arrow next to your calendar at calendar.google.com and selecting 'Calendar Settings'.
- Enter a name and select a color for your calendar.
- In the pop-up screen, enter the following information:Username: This is the complete email address you use with Google Calendar (including the part after the @ sign). If you're using Google Apps, be sure to enter your Google Apps email address.
Password: This is the password you use to sign in to Google Calendar
- Click OK.
Instructions were made originally for Mozilla Sunbird, but also work with Thunderbird+Lightning, although considered an experimental feature.