have a group on Aimoo where I have about 15 different categories.  You need to go to the top of your group page on the left.  You will see the word Options.  Place your mouse on Options and scroll down to Categories.  This will take you to the Control Panel.  Then you type in the name of your category and a brief description.  Click on Save Changes.  Then click on Add Category.  Go back to your group and hit F5 and your category should be there.  Just a note: you should add a sub-category so you can post in your category.  For example: General Board is the category and Daily Sign In is a sub-category.  I would let you see mine but you are not allowed to post links here on General board.  I will post a link on the promotions board though.  Hope this helps you