A Content Management System (CMS), in general, allows you to "dynamically" handle content (primarily text at this point in development, but images also to some degree -- as well as other media such as MP3's). To illustrate this, compare a CMS with more traditional "static" HTML pages. With static pages, each time you want to change or update something on your site, you have to download, edit the page, and upload it back to the server. Only you, and the people who have your access codes, can update the site.
With a dynamic CMS like PostNuke, you only have to upload the site during the initial installation of the CMS. If you want to add an article, you just go to your site with a web browser (from any computer connected to the Internet), and click on 'Add Story', 'Submit News', (or whatever this function is called on your site). A box appears, and you either type or cut/paste the story into the box, then click on the Submit button.
At this point, the story may not appear immediately on the site, since CMS's can be configured so that any visitor can submit a story but a manager must approve the story before it is made available. The site manager, or one of a group of editors that are responsible for maintaining the site, will be sent an e-mail announcing that someone has submitted a story for approval. They will then go to the site, log in with their administrator name & password and decide if the story should be deleted or approved & posted. This occurs with just a few easy mouse-clicks.
Once the story is approved, it will appear near the top of the page along with a small image which indicates the Topic associated with that story. All the other stories move down on the page to make room for the new story.
To summarize: with ordinary, static web pages, you have to do a lot of HTML editing and uploading each time you want to change something on your site. With a CMS, you can forget all this, and just change your site by surfing to it and clicking on the links for updating your site (so if you know how to surf the net, you can maintain your site; very little other work is necessary!).
The above scenario describes only one of the most basic functions of a CMS. It's all you really need to know to maintain a basic site. But there are hundreds of different functions available in an advanced CMS like PostNuke. Fortunately, it's fairly easy to figure out the main functions, ignoring the rest until you wish to use them. But this is the second advantage of using a CMS instead of ordinary HTML pages: the advanced functionality allows your users to search your site, post on forums, leave user information which is easily manageable -- in short, anything that can be done with advanced database management. There are over 100 different 'modules' available for PostNuke, each with its own specific functionality, and new modules are being added every week.
If you think all of this sounds good, you'll absolutely love this... In the description above, we have only scratched the surface of what PostNuke can offer! In fact, speaking technically for a moment, PostNuke has been designed as an ENGINE, and is capable of far more than simply posting news, stories, documentation, etc. The ENGINE of PostNuke essentially handles web site configuration, presentation, and user management. Additional 'bells and whistles' chosen by the administrator can be virtually 'bolted' on to the PostNuke engine. Some may use PostNuke for something entirely different than the "news site" configuration we will be discussing in this manual. Many PostNuke sites are configured as a company Intranet application -- a single point-of-entry for all their internal processes (i.e., project approvals, time tracking, billing, file storage, etc.). PostNuke's only limitation is the imagination of the administrator. In fact, one of the PostNuke developers is giving serious consideration to writing a text-based game (ala Infocom) as a module that relies upon PostNuke's engine -- without a "news" focus at all!