If you need to post a message to the entire school or just to staff members then you can use the Noticeboard in SchoolCentral and StaffCentral depending on who you want to see the message.
Note: if you would like to see how to add an event to the calendar, check out this article.
Simply click on the New Notice button on the Noticeboard to display the new notice panel
2. Complete the Title of your notice along with the Description. You can optionally paste a website link in the URL box. The Publish Date and Time enables you to schedule when you want your notice to appear. The Expire Date and Time enables you to set when the notice should come down. This is a great way to keep everything tidy so that old notices do not appear in the list.
Once you have completed everything just click the Add button to set your notice live for everyone to see.