The Basics: all images made with a modern digital camera (and for that matter film cameras) use three basic controls. These are Shutter Speed, Aperture and ISO.
But you ask what do these do?
Shutter Speed: is the time the the shutter is open, it controls movement and time. Too slow a shutter speed and you have camera shake to fast and you do not let much light into the digital sensor/film thereby affecting the other setting. You need a fast enough shutter speed to freeze the motion of your subjects and if you are moving your own, so that you make sharp images without blur. However, blurred images are also the only way to show time in a still image.
Aperture: this is the opening in the lens that the light travels through too reach the digital sensor/film of your camera. How much it is open affect how much of the image is infocus. Lens range from f1.4 (very fast and expensive lens are even faster at 0.95) to f64. the average fixed lens starts around f2 and goes to f22. (i.e. f2, f2.8, f.4, f5.6, f8, f11, f16 and f22) Our simple way of working this out is the larger f-stop number the larger the depth of field made my the lens. If you want to have a shallow depth of field then you set the camera to the lowest F-stop number. It is that simple, except for the complicating thing that the smaller number is actually the larger opening letting the most light into the digital sensor/film.
ISO: this is the sensitivity of the digital sensor/film to light. It is really the simplest one of the lot, the higher the ISO number the more sensitive the digital sensor/film is to light. The other aspect of ISO is, the higher the ISO the more digital noise/film grain you get.
So every time you make an image with a camera you are using a combination of these settings, even if you are not aware that you are. Even the iPhone does this.