Rules or info when creating a new topic

[dinamik]

Heya,i've searched the forum for this but i havent found what i wanted

Basically i want that on certain categories of my forum,whenever someone is creating a new topic, a box like the one in my picture would apear and remind him the rules, or the way he has to post in there , it would even work if the box were to load a .html page into it with custom content


Thank you,
have a nice day.