How to add this to my board and customize it?
I think they don’t mind that this link is shared, here is the source code of this banner : GitHub - discourse/discourse-signup-banner
But to customize you’d need to fork and edit, which can be tricky.
I would suggest Versatile Banner, this a theme component made for these kind of requests:
As far as I understand this is my link? GitHub - tshenry/discourse-versatile-banner
It seems like meta.discourse.org uses something else, not Versatile Banner component. I am saying this because I cannot really setup Versatile Component to look exactly like here at meta.discourse.org
Discourse used this :
But it is more difficult to customize