How to autofocus on kit lens?

I have nikon d3100 with kit lens 18-55
How can i autofocus, i mean i want to shoot an item how do i set the camera and lens to do the focus? Is this possible?
My lens have a switch A-M which i'm guessing is autofocus-Manual right?
When i do the switch to A and i'm trying to shoot something, looking through the viewfinder or the screen my item is not in focus.
If the lens is switch to A doesht this mean that it should autofocus by itself?
What else do i need to do, change something in menu?

It should, yes, when you half-depress the shutter.

It can be a little complicated, so I suggest you set the central focus point, and re-compose later. Your manual is your friend here.

Yes. On A. Cameras autofocus when you gently press the shutter half-way down.
On M you need to turn the lens and focus it as best you can.

Best to use the camera on full Auto mode ofor everything to begin with.

Sometimes it can't autofocus because the conditions won't permit it.
see the manual.
http://www.nikonusa.com/...oprint.pdf

You are correct - the A means the lens should be autofocusing.

Make sure your diopter is set correctly on the viewfinder (look in the manual to find out how that is done).

When you depress the shutter half way down, the lens should focus. The proper method of focusing is to depress the shutter half way down, let the lens focus, then depress fully to get the photo.

Here is a test. Put the lens cap on the lens and depress the shutter half way down. You should see the lens go all the way to one end and then to the other. This will confirm the focusing is working.

It should be a bit like this (although the lens in this example is different):

First switch camera to AF. A not M. Make sure you are at least 2 feet away from your subject. Point the lens to the subject and press the shutter release button halfway and hold it there. Halfway, not completely down. It will take some practice to get the right feeling if you're new to it. You will hear the lens turn. When the viewfinder (peephole) shows a sharp subject, press down completely.

If you don't get a sharp image in the viewfinder, adjust the diopter. There's a small knob or slider above or beside the viewfinder. Point to something brightly colored and focus on it (press halfway). Release the button while keeping the camera up with your eye looking at the subject. Move the diopter adjuster slowly until the subject is at its sharpest. Your camera's viewfinder is now tuned to your eyesight. Go ahead and take some pictures.

Here is another example of someone buying a Dslr camera and not being prepared for it. I wish you "top contributors" would curtail your recommendation of a DSLR camera to everybody who says they want to take good clear pictures.
And to the questioner Please register and take a class in beginning "Photography with a DSLR" otherwise you will have much frustration with your camera and may forsake it because "people" told you it is the camera type you "must" have.

Why don't you try and read the instruction manual and if that doesn't work because camera manufactures have cut costs by not hiring "tech writers" any more. May I suggest a book written for that camera, available on places like amazon, etc.

Also if you are relatively new to photography may I suggest books written by Scot Kelby. His books come out in small "volumes" and are very easy to understand and on top of that he gives you access to his web site which further explains the points he is making in his books. They run about $15.00 a piece.

A little red light in the middle of the viewfinder indicates where the cameras focusing system is 'pointing' you can move it about to suit your purpose by thumbing the control on th right of your screen left right up and down/