How do I operate the DC motor using this code?

See more:

Arduino

The below code is from this link 15A Single DC Motor Driver wiki-DFRobot[^]

/*
* @file Motor driver DRI0042_Test.ino
* @brief DRI0042_Test.ino  Motor control program
*
* control motor positive inversion
*
* @author bernie.chen@dfrobot.com
* @version  V1.0
* @date  2016-8-10
*/
const int IN1=5;
const int IN2=4;
const int PWM=6;

void setup() {
     pinMode(IN1, OUTPUT);
     pinMode(IN2, OUTPUT);
     pinMode(PWM, OUTPUT);
}

void loop() {
 Motor_Brake();
 delay(100);
 Motor_Forward(200);//Forward, PWM setting 0-255
 delay(3000);
 Motor_Brake();
 delay(100);
 Motor_Backward(200);//Reverse, PWM setting 0-255
 delay(3000);
}

void Motor_Forward(int Speed) {
     digitalWrite(IN1,HIGH);
     digitalWrite(IN2,LOW);
     analogWrite(PWM,Speed);
}

void Motor_Backward(int Speed) {
     digitalWrite(IN1,LOW);
     digitalWrite(IN2,HIGH);
     analogWrite(PWM,Speed);
}

void Motor_Brake(){
     digitalWrite(IN1,LOW);
     digitalWrite(IN2,LOW);
}

However how do I actually control the motor, specifically forward / reverse?
How would I go about adding a potentiometer or forward & reverse switches?
Also I intend to use an ESP32 in this project. As such, I'm aware that I need to include the analogwrite.h library.
Is there anything else I should be made aware of?
Thanks.

What I have tried:

Nothing because I don't see how I can control the motor.