Simple Vertical line

 

Very new to mt4,

Could anyone help me to create a indicator that will trail a vertical line by say 20 candles.

 
int start(){
   static datetime Time0; if (Time0 == Time[0]) return; Time0 = Time[0];
   VLine("20", Time[20], Red);
}

void vLine(string name, datetime T0, color clr){        #define WINDOW_MAIN 0
    if (!Show.Objects)  return;
    /**/ if (ObjectMove( name, 0, T0, 0 )){}
    else if(!ObjectCreate( name, OBJ_VLINE, WINDOW_MAIN, T0, 0 ))
        Alert("ObjectCreate(",name,",VLINE) failed: ", GetLastError() );
    if (!ObjectSet(name, OBJPROP_COLOR, clr )) // Allow color change
        Alert("ObjectSet(", name, ",Color) [1] failed: ", GetLastError() );
    if (!ObjectSetText(name, TimeToStr(T0, TIME_MINUTES), 10))
        Alert("ObjectSetText(",name,") [1] failed: ", GetLastError());
}
Reason: