Alright, all you with your camera previously on the "green square" - did you try out the ISO? Flip your camera to "P"? More about that HERE. We're moving on today, but still practice with different ISO settings so you can see what it can do for your pictures.
Your AF is probably set to Automatic Selection. You want to change that. Let me tell you something you might not believe: you are smarter than your camera - you are human, it is not - you know more. There are still times that I think my camera knows better than me, but I'm working on that. Anyways, YOU know what you want to be in focus in the picture but your camera doesn't - let's say you want to take a picture of your child off-centered - you know you want the child in focus, but your camera might not focus on them because they are off-centered. So never let your camera pick your focus point - you can do it!
Push that AF button mentioned before and scroll until the dot in the middle is lit up - that will set your focus point always in the middle. Test it: when you push your button to take a picture down half-way to focus; when you're looking through the viewfinder, does the red light only light up a dot in the middle? (did you know that to focus a digital camera you push down half-way, let it focus, and then push it all the way to snap the shot?) That red dot shows you your focus point - and you want it right it in the middle.