In the old days of film photography it was difficult to bracket if you didn't want to spend a lot of money in processing and printing costs. But now in the digital age where it costs nothing to shoot an image and nothing to review it on your PC monitor, we can all do it. Here is how it works.
I suppose you could call bracketing an insurance policy against badly exposed images. I must emphasise that it's against bad exposure and not bad images. It's no guarantee that your composition will be a good one. When looking at your images and finding a great composition with the exposure slightly off, it's always an 'if only" moment. Bracketing will limit these moments.
What bracketing does is allows you to shoot an image at the recommended meter exposure setting, one underexposed and one overexposed. But, that still doesn't solve your problem does it? The key here is to determine how much you want to under or over expose the image.
On your camera you'll find a setting denoted 'AEB' for automatic exposure bracketing. By changing to this setting you'll find that you are able to change the exposure by a third, half or a full stop. Depending on how you are shooting, i.e. using aperture value or timed or shutter value (Av or TV), you will either open or close your aperture more or speed up or slow down your shutter speed.
Getting back to how much, is what is going to improve or perfect your image. You will have to experiment to see how much you want change the stops but once you've worked it out the rest, as they say, is history.
So, you've decided how much of a stop you want to bracket, then what next? Simple. Press the shutter button and voila! The camera will take three shots of the scene. One normal, one slightly overexposed and one slightly underexposed. And, I am pretty sure that one of them will be just right. You might find that the best one is the middle exposure and it wasn't necessary for the other two. But, just in case it's a great feature to use on your camera as you learn digital photography.
If you have already tried to experiment with HDR photography you'll find that AEB is a great help to get the perfect final image. Happy shooting!