All staff can add new notices for students. Use this link to add new notices:
If you don't have access to the "School Notices" calendar, you can add it using this button:
The date range defines how long you want the notice to run for.
Make sure you select "School Notices" as the calendar, otherwise the notice will just get added to your personal google calendar.
You can add the notices directly to student caledars by adding them as a guest. You can also add mailing groups or google classroom groups. i.e. if you add firstname.lastname@example.org all Year 9 students will have the notice added to their personal calendars.
The only fields which you need to fill out are "Title", "Date range" "add description", then select "Student Notices"