You can create an announcement to share important information with all users within your course. In your notification preferences, you can choose to receive notifications for announcements created by you as well as replies to announcements you've created.
Type a title for the announcement in the topic title field  and add content in the Rich Content Editor .
In the Announcement Options, you can delay the posting of your announcement , require students to reply to a post before seeing other replies , enable an announcement podcast feed , and allow students to like announcement replies .
Click the Save button.
Note: Unless you are using the delay posting option in Announcements, once you click Save, your announcement will immediately be posted in your course.
Once you save the announcement, it will appear on the Announcements Index Page.