Here is another topic about working on Drupal forum based website. So if u have Advanced Forum installed. Your forum topic should looks like the following picture.
It should be better to add more author information instead of just the username and the user picture. This could be done by the Author Pane module.
1. Download and install the module.
3. After enabled the User Stats module, configure it @admin/config/people/user_stats such that only Forum topic is counted as post count.
4. Now you could find the number of posts by author in the Author Pane.
5. For developers, you could customize the Author Pane template file by copying the sites/all/modules/author_pane/author-pane.tpl.php to your theme folder and modify it to fit your needs.