The real test is if you understand this:

When you short a stock you are actually borrowing shares of a stock from your broker and selling the shares. You owe the shares you sold (shorted) to your broker so you have to buy them back and repay them (cover) at some point. If you are able to repay them (cover) at a lower price than you sold them (shorted) you make money. If you buy (cover) the shares at a higher price than you sold (shorted) the shares you lose money.

http://www.feedthebull.com/content/should-you-short-stocks