In the online world, what you are describing is typically called a "Content Management System (CMS)" Many of the larger sites run a CMS called "Drupal", however Drupal is very complicated and has a steep learning curve.
Among the smaller, simpler, CMS systems, "Wordpress" is very popular. I think one of the reasons it's so popular is because you can host it on their site (WordPress.com), which means you don't need your own server.
If you want to host your own system here is a list of some of the better, simple, CMS systems:
Top 5 Content Management Systems for the Complete Beginner
Note: Wordpress can also be run on your own server.
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought