#include <Servo.h>

Servo servo1; // define servo

int joyX = 0; // give variable to joystick readings
int joyVal; // create variable for joystick value

void setup()
{
  servo1.attach(3); // start servo
}

void loop()
{
  joyVal = analogRead(joyX); // read value from joystick
  joyVal = map(joyVal, 0, 1023, 0, 90); // change value range to 0-180
  servo1.write(joyVal); // write value to servo
  delay(20); // add small delay to reduce noise
}