Well, your own content will come in the form of whatever you input in the stories, sections, and topics areas. When a user selects the story or news item, it opens up and becomes the webpage while leaving the menu navigation so they can access other parts of your site.
For instance, if you go to my site, the homepage has a menu on the left, stories in the middle, what is called a block on the left above the menu headed up Categories, on the right is a block for the weather, a block under that to login or register for the site, and in the center above the stories is something called Announcements.
The Announcements is a module called MultiImage. It randomly displays images and text that I have uploaded to the site using the module to organize it all. The Categories block on the left will display all articles within the selected category you click on. The Weather module will display the weather for the default location of Nashville and let you select your own local if you register for the site so when you login your local weather is displayed.
Perhaps my desription isn't the best in the world, but I hope it does help. Maybe the best way to describe it is that
PostNuke, and other
CMS systems, use programs to provide functionality that you would otherwise spend many hours working on achieving on your own. By using a combination of the core
PostNuke system and modules from third parties, you can provide a wide range of functions and features on your site. You are then able to focus on providing the content that these programs will dispaly for you. What may help is
this group of aritcles [38] that I have written. The focus of this set of articles is to describe in general what a
CMS system, Content Management System, is and how it can help a website developer out.
I hope this helps.