Need help building an EA -- What function is used to modify an open position

 

In an Expert Advisor... What function is used to modify an open position of the chart / symbol that the EA is located on?

Thank you!  

 
Anyone please.... 
 
Neal_Van:
Anyone please.... 

Please visit https://www.mql5.com/en/docs/trading

Documentation on MQL5: Trade Functions
Documentation on MQL5: Trade Functions
  • www.mql5.com
Trade Functions - Reference on algorithmic/automated trading language for MetaTrader 5
 
Marco vd Heijden:

Please visit https://www.mql5.com/en/docs/trading

Yes, I read them.. But still confused.  I need to know which function or functions to use to modify an open position and change the stop loss price?
Reason: