MyBB Community Forums

Hey guys I was wondering How can I create sub forum like this click here
I mean there is no link to post a thread , but when I try to create a sub forum under a forum I get the subforum and right under it says post a new thread

The 'Plugins & Code Modifications' forum is a category, with normal forums inside it. You can't post directly in a category so you need to go into one of the forums.

tnx a lot