Simple website required

Simple password protected website required. Site will allow selected people to view content, share content and version content (i.e. if a document is worked on the older versions of the file are retained). Website must be very secure, there needs to be a shared calendar reminder system in place allowing users with differing levels of access to view particular parts of the calendar. Subjects can be created and a document trail created for each subject. Website should be able to share video media as well.