It is haraam for a girl to put a picture of herself on Facebook or in chat rooms or on other websites, for a number of reasons
The purpose of clothing is to prevent fitnah (temptation), and this can only be achieved if clothes are wide and loose (hijaab). Tight clothes, even if they conceal the colour of the skin, still describe the size and shape of the body or part of it, and create a vivid image in the minds of men. The corruption or invitation to corruption that is inherent in that is quite obvious. So the clothes must be wide.
Seeing a woman with a HIJAB on her head is like finding a diamond amongst some stones. ♥ I don't care what others say...i'll do my duty and wear my Hijaab for Allah Ta'ala. ♥ Oppression and protection are two different things. Islam protects women, not oppresses them."
“Say to the believing men that they should lower their gaze and guard their modesty: that will make for greater purity for them: and Allah is well acquainted with all that they do.” [Q 24:30]