MyBB Community Forums

You know hackforums has the bottom bar for ads how do I make that?
http://prntscr.com/3pc24

The banner one, or the bar with adf.ly image?

Also, try if My Advertisements plugin fits your need.

you can manually add a div in footer with required code & css OR use a plugin ...

eg. <div id="myfooter">your code</div>

see also :
My Advertisements , Forum Affiliate Manager
Index Ads , Dynamic Header and Footer , ...

I meant how did they get the grey bar to hold the adds there?

As Ranjani said, enclose your advertisement code in a CSS class. Make sure you make corresponding css class in global.css