I think she was looking for instructions on how to short a stock, she probably has not done it before. Anyway, all you have to do is choose 'sell to open' when you select the type of transaction. I guess all brokers are different, but 50% of the price is normally the amount of money one needs. If you want more leverage, you could purchase put options instead. It is a little safer(you can only lose what you pay), and has potentially much greater rewards, but a smaller chance of being successful (a stagnating stock causes the time value to diminish).
TA1000, Don't tell her to mess with options. Options will lose you money 85% of the time, STAY AWAY from options. Options are an all or nothing venture, and are BAD for new investors, stocks are challenging enough. You put in your order at the "LAST TRADE" price. You tell your broker to 'Sell Short' the stock symbol and the quantity. Before entering ANY trade, first check the day's volume. If a stock has extremely low volume, you don't want to mess with it, cuz you will move the price as you enter and exit the trade (which is a recipe for losses). The stock should have a MINIMUM of 150,000 shares traded per day on average. Watch the bid/ask spread to guage the amount of people trying to sell (ASK) and buy (BID) the stock. Also, look at the high and low of the day. You should usually NEVER chase a stock after it has already moved over 3/4 of a point.
ALL of the picks I listed made money today. They will make much more in the days to come. I like PGNS and KOPN the best cuz they have the highest potential rewards. Happy trading !