To send message, go to Communicate > Notice Board click on Post New Message button present at top right corner in the notice board page, at click of this button it will redirect you in the Compose New Message page, here enter the details message Title, Message, Notice Date and Publish on, Message To (Select those you want to message) and then click on Save button.

Add post new message image

Here you can view posted message in the notice board page.

Notice board image

To edit posted message click on Edit icon and to delete posted message Delete icon present in notice board page.