first of all you understand stop loss setting you can set a price in your mind which you want to accept its all depend on your knowledge about coin graph and also your risk taking percentage for example you buy one coin in price of 100$$ and you cover loss of 10% then you can use and set stop loss on 90$$
you can place your order on your desired platform then inter your specific stop loss order which you want.
now there are two types of stop loss MARKIT STOP LOSS and LIMIT STOP LOSS,  the 1st one is depend on market condition the order will be executed once stop loss price reached
and the 2nd one is depends on price which you set if markets down and hit your target then its sold but its not guarantee that its fully executed it market moving quickely