The community messages is a place on the wiki that allows admins to highlight things that are important for the community to know about. This space can be used to organize a project, show off new pages, or highlight an ongoing discussion.
The community messages is located on the Wiki Activity page and can be edited only by admins.
If you are an admin, you can edit it by clicking on the "edit message" in the message.
This will bring you to the MediaWiki:Community-corner page where you can edit the content where you can can add as much information as you want
Once the update to the page is finished, click Save. Your changes should appear immediately.
Users who are active on the wiki up to 24 hours after the community corner is changed will receive a notification about the change, similar to the notification for user talk page messages. (like the one below outlined in red). These will disappear after 24 hours if not previously dismissed by the individual users.