1.Go to plus500.com and sign up
2.Verify your phone number - you'll get a balance of €25 (I guess it's like $30-35 for U.S. residents)
3.Send money to any Bitcoin exchange
4.Buy Bitcoins once your money has arrived
5.Open a short position on Bitcoin in plus500.com

Result: If the Bitcoin price goes up your Bitcoin is worth more - if Bitcoin goes down your plus500 balance grows.

Set limits on your plus500 earnings and use potential gains for new positions.

Disclaimer: This is not financial advise.