Hi,
To sync a CalDav to google, you actually do from the online
calendars webapp. You can't sync a webdav, that you view from your
computer, back to a different online calendar program, but you can
read the caldav within google. If it is a public webdav, copy the
provided link, or if it is your own caldav, publish it and copy the
link , and navigate to <
google.com/calendar> and go to the box on the
left side that says "Other Calendars." Click on "add" in the bottom
left and choose "add by URL" then enter the webdav address. Then once
it is added, if it is two ways, then any changes made on the online
google calendar, will upload on the caldav local calendar, then update
to your iCal view of the calendar. Good Luck!