This post is a little old but, to anyone who found this post looking for an answer; If you want to organize your forums into categories/topics, all you have to do is:
1) Create a forum for each topic
2) Make a new page for each forum and place the forum shortcode in them
3) Then make another new page and use it to link to all the forum pages you made.
repeat as necessary for how deep you want your topics to go

You could copy the table html from the forums to make your list look similar.
You can make each forum public or private the same way you would with a normal page.

Hi tataye and welcome to WPMU DEV!

The Forums plugin is perfect for particular circumstances (Multisite usage) but obviously won't suit all use cases. As for a privacy feature, you could potentially put a private forum in a password protected page. Or perhaps use the Privacy plugin to provide some extra privacy options.

You could also use the Membership plugin to make the forums private as well. It would take a bit of setup, but it would provide for a number of other enhancements as well.
http://premium.wpmudev.org/project/membership

There's also other forum options. I'd highly advise bbPress myself, which is now available as a release candidate at the following:
http://wordpress.org/extend/plugins/bbpress/

bbPress is the plugin behind BuddyPress and various other forums, such as this one, and it somewhat recently got updated as a plugin rather than as a standalone installation as it was previously.

It provides for a pretty good wealth of powerful options and has a pretty massive community behind it.

There's also Simple Press, which is equally well supported by a strong community.
http://simple-press.com/

Hope that helps!

-David

i try forums and i'm desappointed.
i thought that i could create sub-forums and make forums public or private.
what should i do ?