To post an announcement which will be visible to all users in your system, log in as administrator and you will see the corresponding menu shortcut, on the top of your screen, located on the right of the navbar(1). Click on the Announcements (2).
This will sent you to the Announcements page, which contains a tabular list of all announcements that you have already posted in your system.
To add a new announcement click on the "Add announcement" button (3), which will open a pop up window with details about your announcement.
Fill in the title (mandatory) and body fields then click add to create the new announcement. If you wish for this announcement to only be available for just a few branches and not system-wide, click to set the branch ownership of the announcement.
As soon as you post your announcement, it will be available for your users in their dashboard