Newbie question: Adding Admin only functions/pages

Hi all, I have another database that collects data from a form on my site. What I would like to do, is create a section in the admin section that allows the admins to generate reports based on this database.

I’m not sure where to start and what best practice would be. Should I be creating a plug-in and adding an extra admin panel? Are there any articles on how to get started with this? (Creating the plug-in and panel only, I’m not asking for code for the report generator)

Also, I am wondering if there is a “report generator” plug-in for WP. That might be a quicker option if there is a way to lock it down for admin only.

Any suggestions would be greatly appreciated.