how and where add arduino sketch in simhub

hello,

first i have to say i am a newbie and have bad english

here is my problem, i would like "by example" add this code in simhub (joystick just been added and i know i could use the new analog axis but i need to understand if possible maybe for other stuff like relay on the same arduino )

do i have to add it on the clientdisplay directly or create a library or is there a specific place to add it?

thanks in advance

#define USE_ANALOG_HANDBRAKE

#define HandbrakePin   3


int minHandbrake = 100;
int maxHandbrake = 300;



int lastHandbrakeState;
int currentHandbrakeState;
int minHandbrakeRead = 1023;
int maxHandbrakeRead = 0;

#include "Joystick.h"
Joystick_ Joystick(JOYSTICK_DEFAULT_REPORT_ID,
                   JOYSTICK_TYPE_MULTI_AXIS, 4, 0,
                   true, true, false,  true, false, false,         // pour activé la fonction RxAxis
                   false, false, true, true, false);

void setup() {
  Joystick.setYAxisRange(minHandbrake, maxHandbrake);
  Joystick.begin();
  
  lastHandbrakeState = analogRead(HandbrakePin);

  delay(1000); //safety delay to flash the code
}

void loop() {
#ifdef USE_ANALOG_HANDBRAKE
  currentHandbrakeState = analogRead(HandbrakePin);
  if (currentHandbrakeState != lastHandbrakeState) {
    Joystick.setYAxis(currentHandbrakeState);
    lastHandbrakeState = currentHandbrakeState;
  }
}
#endif