The full group meets in video conferences biweekly. The usual schedule (as well as information for joining the VC) can be found on the offical W3C Calendar but there is also a Google Calendar event that is kept up-to-date e.g. in the event of cancellation. Contact the chairs to be added to it. The agenda and notes are kept on GitHub in the meetings repository.
There are also several subgroups that maintain their own meeting schedule and agenda. A list is maintained and their minutes are kept in top-level directories in the meetings repository.
All attendees are required to be members of the community group prior to attending.