How do they reach such quality in photography?

I'm a big fan of photography and I own a Nikon D90, but I'm a beginner and I know very little about photography. I was visiting this website:
http://www.ebruceylan.com/photography/photography.php
and when I look at the photos, the colors and the quality really fascinate me. It is just that I have seen photos with such colors on flickr too. My question is that how they reach such special colors and quality with a photo? The photos are dark and gloomy and dreamy, and I have no idea how they create such effects. Do they use Photoshop, or is it just their camera?

I very much doubt that the colors come from the camera. Sure, professional cameras are great but never like this. Most photographers do batch edits on Photoshop. Look into some tutorials. Some of the photos do look real but does that have dark edges around the subject usually are not. (see first photo on website)

Quite possible to do those with your camera.
All you need is knowledge of basic photographic technique, lighting and post processing.

Don't try and run before you can walk.
Photography is like any other skill, you need to learn and that takes time.

Principally good lenses & good lighting. Not shooting in Auto modes - learning about exposure & making the decisions about exposure, not leaving it up to the camera.

Most of those on the front page look like some additional lighting was used (off camera flash). Some of them (Workers for example) have been post processed (looks like a high pass filter applied).

Almost all are using lots of natural light, fill flash, edited in a photo editing software to add and remove color and to darken. Proper placement of the camera, the subject, and the sun. Remember people put up the best of their work and not every shot is a keeper.

They get a qualified image then use Photoshop.