its really easy to start trading Bitcoin. You can buy actual Bitcoin at a place like Coinbase, then send it to your wallet. It transfers in seconds and is free to send. Its really cool to see how fast it oves.
Then you can send your Bitcoin to an exchange. I like Bitfinex. They allow you to trade on margin with leveraging of 3:1.
There are also digital currencies even newer than Bitcoin called altcoins. They are more like penny stocks. i've even seen them up 1000% in some instances, but there is alot of insider stuff going on.
If you want to turn it back into dollars, you can just do a wire transfer from bitfinex, or use a Bitcoin ATM