How to show notification bar if there is a new post in Wordpress?

Can someone help me with the following. I want an alert bar at the top of my Wordpress website, when there is a new post published on my blog. So the users are known that there is a new post available.

So I downloaded a Wordpress plugin called: WPFront Notification Bar Only the problem is that I only can set this bar on or off. But not show this bar automatically when there is a new post and after a day it will reset the value to off and will only be switched back to on if there is a hole new post.

So I thought if I make in my header.php a notification bar like the plugin, style it to my website and add some javascript to it. Only the problem is, I don’t know how to do this and also can’t find something on the internet so the reason for this question is written above.

Hopefully someone can help me out!