To make any changes to your Announcements forum go to the Gear menu (cog icon, top-right) and click Turn editing on.
To send a message, go to your Announcements forum, click Add a new topic and compose your announcement. You can insert images, audio and video, and attach different types of files. You can also enable the announcement to appear for a determined timeframe under Display period.
To add a Latest announcements block, which will show the three latest announcements at a glance, go to the hamburger menu at the top left of your screen and scroll down to the bottom to select Add a block. Then select Latest announcements. Once you have created the Latest Announcement block you can open the Gear menu within the block by clicking on the cog icon. From here you can configure or hide your announcement block, edit or check permissions.
To hide the Announcements forum from your course site click Edit to open a drop-down menu and select Hide. The Announcements forum is now hidden from students until you return to Edit and select Show.