aruindo to read my xbee accelerometer data

yes i agree am totally wrong but really coding is not my thing , am sorry if i wrote stupid code and i wanted you to explain .
however i did another aproch and am getting data from my serial port but they r not correct .
can you check this code please

void setup(){
  Serial.begin(9600);
  delay(100);
  Serial.print("reading.. ");
  Serial.println();
}



void loop() {
  
  readPacket();
}

void readPacket(){  
  // if serial has 18 bytes which what we need int he buffer my every packets contains 18 bytes 
  if (Serial.available() >= 18)  {
   // FIND MY START BIT 
    if (Serial.read()==0x7E)
    // read the value we do not need out of the buffer 
   for(int i =0 ; i< 11 ; i++)
   
    byte discard = Serial.read();
   
   //which contains x value for my 12th byte and 13 byte 
   if(int i=12 )
   {
    int analogHigh  = Serial.read( );
    int analogLow = Serial.read();
    x = analogLow + (analogHigh * 256);
    Serial.println(x, DEC);
   
   }
 
  else
    // he is for my y value for my 14th and 15 byte 
    if (int i=14) {
    int analogHigh  = Serial.read( );
    int analogLow = Serial.read();
    y = analogLow + (analogHigh * 256);
    Serial.println(y, DEC);
    Serial.flash ();
    }
  else 
    // here is for my z value 
    if (int i=16){
    int analogHigh  = Serial.read( );
    int analogLow = Serial.read();
    z = analogLow + (analogHigh * 256);
    Serial.println(z, DEC);
    Serial.flash ();
    }
  }

 

  }