This guide should explain the basics that are common to all addons, however. Creating an addon and registering it with NewsPro is very simple. Addons must explicitly register themselves with the Addon Manager to appear there. When the script reaches one of these points and sees that an addon has hooked itself in there, it will run a specified subroutine in the addon. Basically, it is as if code from the addon was inserted into that point in newspro.cgi.
Hooks are present in quite a few places in newspro.cgi.
Next, the addon has to hook itself in there. That's about it. The difficult part is, unfortunately, figuring out how newspro.cgi works. We need an example here, and a good example is an addon that displays a list of headlines on the Submit News page. Fairly simple, and possibly useful as well.