Aperture, well that's a fun word to say, if only I knew what it was....
When I started shooting photography, I set my camera on manual after the first day I got it because I did not want to use the automatic functions, I thought to myself "I can do better, let's be better" so I steered away from those auto functions, problem was for the first yearish I seriously had no clue what I was doing. I had a grasp on shutter speed, but I had no clue what aperture was I knew I bought a lens that allowed me to have a blurry background but I wasn't seeing the blur. So I started doing research, and a simple Youtube video cleared everything up for me, so just know it's okay to ask for help rather then trying to figure everything out on your own, it may take a while.
So let me see if I can help, the actual definition of aperture is "The opening in which light enters the camera". This is the function that will allow to you to determine the depth of field you would like, which is the amount of blur you would like. This also goes without saying the amount of blur you would not like. Aperture works in two different ways, the first is it allows more light into the camera so you have the ability to shoot in low light situations as well open wide up in the mid day or whenever, but it gives you the ability to shoot at a very fast shutter speed. The second is this, the more light you let in to your camera, the more blur you are allowing, for instance if you were shooting a portrait and wanted that nice blur in the background, this function is for you. The more you close down the aperture, the less light you are letting in, which determines less blur, such as if you wanted to shoot a really cool mountain and you wanted everything to be in focus, you can close down. Does that make sense? If not let me say it a different way...The more light you let in, the more blur you get. The less light you let in, the less blur you get.
Did you guys know our eyes are lenses? Yup, that's right! Our eyes view around 50mm from right to left, also our eyes have aperture's. When you enter a dark environment, your eyes adjust the aperture in your iris to allow more light in so you can see better, this also works when you are in bright environments, your aperture's shrink (close down) because you do not need to let in that much light in to your eyes. Do you get it? This is why the 50mm lenses are so popular, it mimics your eyes.
Aperture is one of the hardest things to fully understand in the photography world, but it is essential that you do understand it. For me, being in the Wedding industry it is the driving factor of my foundation in photography. What I mean is, I always determine my aperture, then change my shutter speed accordingly, even when I use flash.