Yeah, I've never had a clue how to accomplish that. So, today, I wandered to a public garden with my camera, looking to play Ansel Adams for a while. There's a little man-made waterfall there, and I sat on a bench, playing with the camera, whacking those random settings, and trying to figure out how I was taking totally black pictures on a bright, sunny day.
After I figured out what I was whacking, the light came back to my camera. And my waterfall pics looked like ALL my waterfall pics. Like this:
It was starting to piss me off. I wanted wispy, damn it! So even more maniacal button whacking commenced. More lumpy water, more underexposed pictures, more cursing happened. But then, I whacked something good. And finally, FINALLY, I hit pay dirt and produced: