Normally you just enter the name of the list and optionally a description. If you select
a synchronization service, then additional fields are opened for specifying details
of the synchronization.
For the time being only Google Calendar with Google accounts is supported.
Google Apps accounts cannot be used directly, but their calendars can, if they are
included as shared calendars in the Google account.
You must enter the account name (Google Mail address) and password and then you
must select the Calendar name from a list retrieved for this account. The Sync Type
(writable or read-only) is automatically detected and shown.
See more details on Google Calendar synchronization here.