Support Forums

I'm sure you guys have noticed on SF and HF that all of the forums aren't just straight down the page, causing endless scrolling. My question is now, how do I create these tabs? Is it a modification to the CSS or something else?
If anybody knows how to do so could you please tell me how to.
Thank you.

SF and HF use a plugin Omniscient has created named "Tabbed Menu": http://www.mybbcentral.com/thread-7687.html

There is also a similar plugin for free: http://mods.mybb.com/view/mytabs

As said above. I would suggest purchasing an upgraded membership at mybbcentral. All of Omni's plugins are there.