How to create a custom warning message before posting

Hi,

I am one of the admins for our own discourse space, where we discuss amongst other things privacy and disclosure issues for the software we develop. One of our team members would like to create a warning message to ensure our community members are mindful when discussing such sensitive topics. I have created a mock-up image of what we’d like to see:

what we currently see while writing a post as an ordinary user

what we would like see while writing a post
Imgur

Do you have any advice on having multiple advice screens pop up as you start writing your post? I can’t see what to do in the administrator settings, but i’m not very practiced at customising discourse settings, we mostly just use it as a very basic forum.

thanks v much,
Alex

PS why can’t i embed media as a new forum poster? I completed the training, and read the community rules! Now i’ve just had to spend time uploading to imgur for exactly the same final result…