In order to understand the 3 Towers of Exposure first you must take the courage and leave the Auto comfort zone and turn into the Manual side. Go ahead you can do it! there, that was not so bad right? Now the fun begins! Photography is about light and how you control the light and make it bend according to your will can truly bring out the Art in Photography..
1. Aperture ( F-Stop ) - f2.8, f5.6, f22 is the measurement on how open your lens is to let the light in to expose your image. A fully open faucet will let more water out than a partially closed faucet, water is light in this example the more open your aperture is at f1.8 the brighter your image will be for more light is coming in to expose your image than a f22 with a almost closed aperture that stops the light from coming in to expose you image as a result you have a darker image. Now, control that Aperture to your liking and not your cameras liking.
2. Shutter Speed - Now here is a fun one, Speed! We all love to Speed up specially when we are in a vehicle in photography speed can be a form of art. 1/10 of a sec. to 1/250 of a sec. is the measurement of the shutter of a camera, how fast can it blink the faster it blinks the less light it lets into the sensor to expose your image, the slower it blinks the more light it lets in. You want a brighter image? slowdown your speed but do not make it too slow for you will get a blurry image unless that's what you are going for. You want a darker image? Speed up your shutter it will not only stop the light from coming in but it will also freeze your moving subject and get a sharper image. Now, be a Speeddemon or a Sluggish Snail its up to you, the best thing is you are in control not your camera.
3. ISO - And if Aperture and Shutter Speed is not enough? ISO to the rescue! Lower number is always better for our friend ISO for it makes it pretty, while higher number can make it ugly. If you need more light if our friend Aperture can't satisfy you? give ISO a chance bring those numbers up and the light will shine on you just make sure you don't put it so high that it makes ISO ugly and full of dots or as in photography world would say NOISE!
There, be the Master of your Instrument and Control the 3 Towers of Exposure and bring out the Artist in you! Thank you