If you would like important notices / announcements to be posted on the main page of your help desk you can setup a KB category to handle all announcements.
Here is how you could get started:
- Click on "Content"
- Click "Add Category"
- Name a category "Announcements"
- Go to Administration > Settings > Public Settings & Styles
- Edit the default desk
- Scroll down and check the "customize startup page"
- Select "Recent knowledge base articles"
- Choose the category named "announcements"
Once this is setup any content posted into the announcements category will show up on the startup page of your public help desk.