What's your percentage of "in-focus" shots when you're shooting action photos (sports, birds, etc.)? If it's less than 90 to 95%, you don't underand the settings. Don't feel bad, it's far from simple and 90 to 95% of camera owners don't use these features properly. Watch these videos to get a better understanding of what you can do to improve your focus.
Autofocus. Improper focus means you've lost your image.
"Backbutton" focus. How pros stay in focus.