Ever noticed the messages WordPress displays when you activate a plugin, or save settings? Or the messages that some plugins show in the dashboard, perhaps notifying you of a missing requirement? These are called Admin Notices and I’m going to show you how to add your own in your plugin or theme. They’re really quite easy to add.
To display an admin notice, we’re going to write one function, and it can be placed just about anywhere. If you’re trying this with a theme, then I recommend you place this in your functions.php. If you’re trying this with a plugin you’ve just started, then I’d recommend placing this in your main plugin file. The function does nothing more than echo out the message we’d like displayed. The message is wrapped in a little bit of HTML that will style it the same as the built-in admin notices.