typically you'd either use a limit order above current market spread, at the point where you plan to take profit, or you use a "trailing stop" with a given relative distance. The trailing stop will be pulled upwards when the market rises, but remain at a fixed level, when the market falls, so it becomes a stop order eventually. Note: the value entered for trailing stops is a relative value, e.g. 3 means 3$ below current selling price.

Be forewarned though, trailing stops are especially hard to set right.
Either they trigger too early (caused by a small jerk downwards, before a huuuuge rise upwards), or they cause losses when set too far away.


P.S: obviously everything in reversed direction when you're short