I need paxil...what is this again? some anti-depressant. sigh...?

Can someone please tell me what are the symptoms of depression, and how do you get it?! why does it happen to some and not others. how is it a chemical malfunction of your brain? i promise i'm a smart girl...i always have been. but i frickin can't concentrate on any ignments 'cuz i feel like giving up. i find myself saying...what's teh use, you're going to fail anyway. what the hell is wrong with me. will one paxil pill do the job and make me feel happy again and make me concentrate and be determined for my exams. why the hell is this happening to me. i hate this, and my life.