Thanks for posting.

With SimpleForm, there isn't really a concept of "categories" or "sub categories".  

You can create as many forums as you like thought.  

For example, in our setup, we have 6:

http://www.interactivetools.com/forum/forum.php

There is no limit to the number of forums you can create.

Does that help?

Let me know any questions.

Thanks!

Just wondering, how many forum categories / subcategories can I use with the Simple Forum category plugin?

Thanks!