peihao83,
I just want to tell you that I know how you feel.
I bought a D90 not knowing exactly how a DSLR works. Like you, I read the manual already, but I didn't understand it although it's in English.
So I put it aside, google instead, for whatever I want to know. The world of google seems more useful to me because some websites would explain in simple terms.
For me, I am not concerned about the technical aspects as long as I get pictures that I feel 'wow! This is what I want, or more than what I ask for.'
Somebody in this forum shared the method he uses:
1) Shoot in P mode. 'P' is programmed mode, which means the camera does everything for you. It's better than Auto mode because the flash doesn't pop up all the time.
2) Look at the ... exif file (do you call it that?) and take note of the different readings ie. aperture, shutter speed, ISO etc.
3) Try it in A (Aperture) mode, where you just adjust the aperture OR
4) Try it in M (Manual) mode, where you adjust the settings the way you like it.
This method helps me alot in using the camera.
You need to keep shooting to realise what you want. At first I also didn't understand what this means - keep shooting. It's like if you're committing a mistake, you wouldn't know, right? So you need to look at others' pictures and perhaps try to create something to that effect. It does not mean the same setting, or subject.
For me, at first I just wanted sharp or clear pictures.
Then later, I wanted more, because I kept shooting and looked at others' pictures to know what constitutes better pictures.
Many months later, when I understand the camera better, know what is 'aperture', 'shutter speed', 'ISO', and why sometimes the shutter doesn't shut altho I had pressed the button already, and sometimes I use manual mode, I find that the manual seems to make abit of sense. I still don't understand many things in the manual. By reading over and over again, it doesn't help me. But whatever I want to know, and feel that the manual can't give me, I google.
I still don't understand 'depth of field', and a host of other things, but nevermind, as long as the pic looks good to me, can already. I know I'll understand it sooner or later.
Hope this helps.
Oh, when I said 'keep shooting', I also mean 'For the same picture, shoot a few times to get the effect you want. Adjust the zoom lens, or the aperture, or the shutter speed, or the ISO to try different settings'. I used to think that all good photographers only shoot ONCE for the pictures they want. A colleague told me the professional photographers would shoot a few times to get the shot they want. So by all means, shoot at the same thing over and over again, and adjust the settings differently, until you achieve the effect you want. Usually I adjust the aperture and the difference would be quite substantial.