@ serpent :
There is a mode dial that has 4 important modes Auto, Program, Aperture Priority, Shutter Priority and Manual. Apart from that there is another dial that controls (clockwise from top) tracking/exposure/selection; flash; timer; and focus.
In Auto mode camera uses its brain, you do labour work by pressing shutter key
In program mode, you get another option to change exposure and flash modes. The most imortant control in this mode is ISO which is set to Auto in Auto mode. For noise less images, you need to use the least possible ISO. Auto ISO is pretty high resulting in Noisy images. However if you set ISO 80 in dim light shutter speed may go very high in hand held blur.
In Shutter priority, and aperture priority, you can choose shutter speed or aperture value and camera adjusts the rest
In Manual, camera takes rest, you use your brain and do all the labour
In most of these modes in bottom right corner you should see a scale with 5 graduations. This helps you set the exposure. There is a pointer that moves when you change shutter or aperture value. When the pointer is in middle, it means your photo will be perfectly exposed. BEWARE that this scale does not give the right info when flash is on. You can disable flash then try playing with these settings.
Try to visualize the difference between what output you are getting from the camera and what were you expecting... Like your pics in another thread are very dark but that can be made perfect by moving the camera an inch away from the flowers.. No settings required 
So expect and shoot
