It's not hard to create new categories on your forum. Just make your way to the admin panel, select "Categories" link and fill the field.

http://i.imgur.com/PpLRAPQ.png

To create a new forum (section) navigate to "Forums" link and add your new section:

http://i.imgur.com/zCTCcDp.png

After that, you can manage the forum's name and its description.