Trailing Stops on Mt4 trail your stop by a fixed amount of pips decided by you. A trailing stop set on an Open position will only activate after it has moved in your favour by the number of points set for the trailing stop away from the Open price. Essentially once the trailing stop is activated it will be at break even.
To place a Trailing Stop on an existing position:
1. On the Instrument Chart, right-click the trade you would like to add a trailing stop to
2. Using the drop-down menu, select to Trailing Stop distance which is required for your position. The Trailing Stop will be automatically initiated when enough difference between the Market price and your Order price has occurred
3. This is the only method to add a trailing stop