Step 3: Manual vs Auto Exposure.
"But ledzeppie, why can't we just put the camera on auto? It's so much easier!!!1!!!11!!!"
Well Jimmy-Bob-Junior, we don't put the camera onto auto exposure because manual mode gives much more control over the picture. Often, using auto exposure can remove the atmosphere from a picture. For example, this picture that I took was taken on a very cloudy dark day, and to capture the atmosphere I raised my shutter speed, lowered my ISO, and closed my aperture, to darken the picture. This really gave a good mood to the picture, something that auto wouldn't give me. Beyond this though, auto exposure also only determines how light or dark the picture should be based on one point. This means that often certain parts of the picture will be too dark, or too light. This is common with the sky, as it is usually lighter than the ground.
Essentially, auto exposure can remove the artistic part of the picture.