Scottrade, Zecco, Etrade are a few.  You will need at least one year of education and training before succeeding unless you are lucky.  It is better to have a mentor someone you know who has experience in stock market to teach you, your family or friends is the best choice.  It is wise to have substantial amount of money to trade full-time otherwise you can trade part-time. 

Before, you trade any real money, trade on demo account as much as you want, that will give you simulation of the real market, don't come out of demo account until you succeed well.  Watch CNBC, bloomberg or other financial news.  Read Financial Times, Wall Street Journal, and other Financial news.   Careful from whom you get advice from.  Don't take any advice from someone you don't know. 

I give free advice only to family and friends from Skype, cellphone, and email.  

Good luck.