That's good bud that you took only a $65 hit. Many people must be down huge - It was quite unfortunate - Even for those who tried to play the bounce - It will be even more unfortunate if the company was hiding things from the investors (as some articles are claiming, hence the investigations).
I am all cash now. Covered the last position at close. Shorting is just the opposite of going long. Just click sell first (assuming you have no positions) - your broker will give some kinda indication that you are creating a 'short position' - Then later click buy, and your broker should say 'buy to cover' or something similar - May be different for different brokers. BUT they gotta have shares to short. My broker always has shares for Bio stocks. I usually go long and short on the same stocks over and over again till they are volatile, when they lose volatility, I move on. Its very common to jump on a stock thinking that its oversold and 'has to bounce', but they often bleed more before making a U turn.
My eyes will be on ARIA for a while. If there is more panic, and the 4.20s break, I will short again. The company needs to get their act together before we see a true reversal IMO. And after that, the bounce will be awesome, I'll play long.
P.S. My Bio list - HAL$ - XOM$ - ACA$ (took a bad hit lately) - All Baker Bros stuff (their stocks are good IMO). ARIA is just for temporary play for me.
Good luck and have a great weekend.