Like many systems, WordPress may not do everything you want right out of the box. Instead, it focuses on a set of core features and allows for customizations in the form of plugins, so if the built-in functionality doesn't meet your needs, your options are to:
Find an existing third-party plugin
Write your own plugin
Look for another CMS entirely
It is well worth your time to search for an existing solution if WordPress doesn't already have the functionality that you require—chances are high that someone out there has already done what you are trying to do. It may not be as much fun or as glamorous as developing your own shiny new code, but it is usually easier and faster to cash in on the work others have done, just be aware that a lot of code in the WordPress repository is written by amateurs and it may contain bugs.
If you do end up extending WordPress with your own plugin, and we hope you do since you are reading this book, make sure that you are doing one of two things: either you are solving a problem that nobody has solved before, or you are coming up with a better mousetrap and re-solving a problem in a new and valuable way.