[ue]

I have some questions. I'm new to SLRs and I got the D40. I've read a bit about some of these things, but I just don't get it.

1) Aperture: how is it supposed to help the image?

2) Shutter: shutter speed and everything doesn't make sense! When I turn the dial too much it goes pitch black, am I going too high for 1/___ sec? I think so but I don't know how to get it just right. Like a waterfall - how to make the water blur or froze.

3) Get rid of washed out skies. I think that's the right term, the skies in some of my photos just look like crap.

4) Tips on night photography.

I mostly do urban scenes for photography. I am just new to SLRs but I really like them and I really really enjoy photography so it bugs me when this stuff comes up.(Shutter, etc.)

Thanks.