If you're not sure what you're up to, you shouldn't be investing. The stock market is not a game.
If you want to play an expensive game, I'd suggest blackjack at your local casino.
I would actually suggest the opposite. If you have a lot of money (eg $5,000+) I would suggest investing it in the stock market. Get a broker and wait a couple of months until the summer for everything to bottom out.
Gambling it is just a waste. At least you can invest it at the moment. Check out bonds while you're at it.
Charles Schwab is a great investment brokerage bank. Check out the free investor checking account. I use it and I love it!