It may seem odd to talk about using an application to manage your content now after you've worked through 20 lessons explaining how to build web pages from scratch. However, those skills will serve you well whether you use a content management system or not. Content management systems can take a lot of drudgery out of web publishing without limiting the amount of creativity you can apply in designing your web pages.
Some work is involved in learning, setting up, and customizing a content management system. When you're creating a website, it's probably easier to start with just a few static files and leave aside the content management system. As your site gets bigger, though, at some point the work involved with dealing with static files offsets the initial investment required to start working with a content management system. You have to figure out whether that initial time investment will pay off in the end.
Another common tradeoff with content management systems is that they vary in flexibility. Some, such as photo galleries, are built to handle very specific kinds of content. You wouldn't use photo gallery software to manage an online news site, for example. Others are more flexible. For example, the Mambo content management system is designed as a generic content management system for any type of content. Generally speaking, the more flexible a content management system is, the more work it is to set up. So if you know you're publishing a photo gallery, setting up a photo gallery package probably makes more sense than setting up a general-purpose content management system and customizing it to present photos.
In Lesson 18, "Putting Your Site Online," I talked about the various options for web hosting. A similar set of options is available when it comes to content management systems. You can write your own. This provides the most flexibility, but it can be a huge amount of work. You can install and manage an application that someone else wrote and customize it for your own needs. Generally to go this route you'll need your own server or at least an account with a web hosting provider. The final option is to subscribe to a hosted application. For many kinds of web applications, you can pay to subscribe to an application that's hosted by someone else. They make sure that the servers stay up and that the application is running properly, and you just focus on entering your content and making whatever customizations are available. Hosted applications are generally the least flexible, but they're also the easiest to get started with.