Open Source Document Management System | OpenKM

Good day! I've been using OpenKM 5.1.5 + MySQL.
I'm just wondering how can I add some tabs in the document properties window just like in the online demo?
In my OpenKM version, when i click a document it shows only Properties, Notes, Security, History, Preview..
I just want to add forum and contact tabs. What is the first step in order to do this?
Hoping to give me some help. Thank you!

As you can see in our http://wiki.openkm.com/index.php/User_Guide ( user guide ) these extension are packed as professional extensions ( at bottom ) and are only present to our customers.

The idea is that some extensions are only available to our customers but it's and extended api http://wiki.openkm.com/index.php/Extension_Guide for creating your own extensions and share with community, there's no problem on it.