What is it you are confused about? Take it one step at a time. Photography is NOT an exact science, it can be, but it doesn't have to be. It is what you want it to be.
It is actually very simple, but made complicated. In a nutshell:
light comes from a source (doesn't have to be the sun) and illuminates certain objects.
You capture the light illuminating the objects by directing it through th elens to your film or sensor.
That is it. That is all photography is.
Now, to complicate matters you have CHOICES. You can choose your viewpoint,
your lens,
your aperture and
your shutter speed.
But those are the only choices you have to worry about.
You need to balance a few of those choices, but that is the learning curve, you are simply learning to balance the elements. It won't come in a flash (ho, ho), you will need to work at it, and keep working at it and you will stillbe learning new tricks in 30 years time.
Enjoy the journey of enlightenment.