Stoploss is very much important because it help us to minimize our losses. You should use stoploss on your each trade and you should place stoploss in such a way if it is hit then you are sure that the price action was not ready to move in your favour, the Price Action has reversed....
You should place stoploss at the Previous Swing High (If you have taken a Short Entry (SELL)) or at the Previous Swing Low (If you have taken a Long Entry (BUY)).
I have attached a Chart of my Previous Trade, which will show you where did i placed my Stoploss and it will explain you in detail, what do you mean by Previous Swing High and Previous Swing Low....
For more details on how to manage your trade read Money Management Technique provided in the First post of this thread....
mazprofx.