Macs have long had the reputation of being computers that you don't need hefty manuals to use. That's true, but that's not to say that documentation has no place on the Mac - it's just built in these days, thanks to a core feature of OS X Mavericks called Help. It's a menu that's often ignored, and it shouldn't be - even for experienced Mac users.
Help Center is absolutely one of the most underutilized resources in the operating system. I see so many questions posted to Internet forums and social media on a daily basis that can be answered through Help Center. It should definitely be your first line of defense if you run into problems or don't understand how to use a feature of an application.
Here's a step by step guide to using Help:
Select Help from the menu bar at the top of the screen
Type the subject or issue you're trying to find help about in the Search field.
Alternately, several menu items should appear that will give you access to more assistance. The menu will change based on what help services the developer provides.
You can click on links to get more details about subjects that interest you or provide you with the details you need.