Scottrade (basic web based trading platform) account is free with a $500 minimum to open an acct. TradeStation which is one of the preferred Day Trading (full software running on your computer) and brokerage services has a $5,000 minimum to open an account and also live data will cost a minimum of $105 a month unless you trade 5,000 shares a month and then they wave $99 of the monthly fee.
Be prepared to lose all of your startup money. You can avoid losing it all if you go very very slow and small and also add to your account when possible. At first the risk is high because you don't know the pitfalls to avoid but after a while after you have stepped in a few, you start avoiding them. You still get your feet wet every once in a while but not as often.
I'm not an expert by any means but I have been reading and studying a lot. I consider myself a noob. Best thing to do is read read read and study charts for hours a day until you can start recognising patterns. At that point, keep doing it.
I think it is fun and exciting.
Oh, and you can trade US or any other markets.