Board Thread:Support Requests - Getting Technical/@comment-25118285-20160807201833/@comment-29138396-20160807202315

There is no native way for an admin to create custom site-wide notices. This is something only Wikia Staff has the ability to do and they only use it on a global scale.

The  page is only for use with the MonoBook skin and it will not work with the skin you see by default. Instead you will have to look into javascript solutions such as the WikiaNotification script.