Remove blank space in forum just below the header

[tur]

I'm not sure if this is the correct place to ask this but I'm trying to work on the layout of my forum and I have a large blank area that I'd like to remove or possibly put an image into. How do I go about finding where this space is being allocated and how to modify or add to it. 
The area in question is just like where the bird image is here on the support form. 

[Kami]

That blank space is where an ad normally goes. Is your forum possibly new, ~2 weeks old or less? Or do you have an adblocker enabled?

[Scott]

tur, looks like your forum recently added a custom domain. When this happens it generally takes a couple weeks for ads to appear on the forum again.