Mate,No worries, traders can short sell stock like QBE a few...

Mate,

No worries, traders can short sell stock like QBE a few days ago after the div at say 21.50 this is a strategy that traders use to sell stock that they don't have so it is called short sell and buy back or close their position at say 20 so they will make 1.50 profit, or in option trader we will buy puts or sell calls when we feel stocks are coming down so in the above scenario we will buy say april put with strike 21.50 so when the stock fall the premium of 21.50 strike will have gone up.

Longs are just the opposite of short as they expect stocks to go up and they can use physical stock, options or CFDs.
it is going to be to take lots of space to explain all in details so hope you have a better idea, traders like myself will use those strategy and go long or short to try making money in any market situations.

Cheers,