The URLs you posted are for the titles.
I'll take the super-simplistic tack first, probably too simplistic, but bear with me...
Say that there is a "Color" category. It has 6 sub-categories, or forums; Red, Orange, Yellow, Green, Blue, and Purple. You want to post something about... um... whether the grass is greener on the other side of the fence. So you click on the "Color" category. Hey, no "new topic" button! What gives?
"Color" is not a forum... there is no way to post to "Color." You have to choose one of the sub-categories, or forums. So you decide your question best belongs under "Green", and you click on that. Voila! A "new topic" button.
If you use the FORUM INDEX, you shouldn't have any of this confusion, because all of the sub-categories, or forums, are all laid out.
http://www.able2know.com/forums/index.php