What camera lens do i use each for? 18-55mm or 55-200mm?

Im very interested in photography and have brought a new slr, a nikon d5000. while i am very interested in it, i dont know much about the techinical side, i have a basic knowledge of aperture and shutter speed but now that i have to change lenses, i dont know what each is for? is one a wide angle lens? the one that shows more the 18-55mm one is the one i prefer, but am i not meant to use thsif or portraits etc? and i dont unederstand, it shows more but it is smaller? what should i use for what. please help guys!