HELP - Online Stock Trading in USA

Hi all,
I've been searching for some ideas on how to do stock trading in US Stock Markets(SM) but could find info only about Indian Stock Markets.
Can someone pls suggest on how to start doing online stock marketing in US.. i mean from the basics.. what are the rules..
Please pour in your ideas.. If someone is already doing it, then it would be great help if they can guide us through this..

Please try to learn stock market from basics and then trade. DO NOT EVER TRADE WITHOUT KNOWING HOW STOCK MARKET WORKS.

Happy investing and trading!!!
Devi Naren