Media Player Keys with Rotary encoder for volume?

Hello all, I'm very new to Arduino coding, and I'm building a switch panel for a multimedia setup. I have everything working other than my volume knob. I can't understand how to merge working code properly. Here's my code so far=

/* Buttons to USB Keyboard Example - Special Media Player Keys

  You must select Keyboard from the "Tools > USB Type" menu

  This example code is in the public domain.
*/

#include <Bounce.h>

// Create Bounce objects for each button.  The Bounce object
// automatically deals with contact chatter or "bounce", and
// it makes detecting changes very simple.
Bounce button0 = Bounce(0, 10);
Bounce button1 = Bounce(1, 10);  // 10 ms debounce time is appropriate
Bounce button2 = Bounce(2, 10);  // for most mechanical pushbuttons
Bounce button3 = Bounce(3, 10);
Bounce button4 = Bounce(4, 10);  // if a button is too "sensitive" 
Bounce button5 = Bounce(5, 10);  // you can increase this time.
Bounce button6 = Bounce(6, 10);

int led = 12;           // the PWM pin the LED is attached to
int brightness = 0;    // how bright the LED is
int fadeAmount = 1;    // how many points to fade the LED by

void setup() {
 // declare pin 12 to be an output:
 pinMode(led, OUTPUT);
 
 // Configure the pins for input mode with pullup resistors.
 // The pushbuttons connect from each pin to ground.  When
 // the button is pressed, the pin reads LOW because the button
 // shorts it to ground.  When released, the pin reads HIGH
 // because the pullup resistor connects to +5 volts inside
 // the chip.
 pinMode(0, INPUT_PULLUP);
 pinMode(1, INPUT_PULLUP);
 pinMode(2, INPUT_PULLUP);
 pinMode(3, INPUT_PULLUP);
 pinMode(4, INPUT_PULLUP);
 pinMode(5, INPUT_PULLUP);
 pinMode(6, INPUT_PULLUP);

}
void loop() {
// set the brightness of pin 12:
 analogWrite(led, brightness);

 // change the brightness for next time through the loop:
 brightness = brightness + fadeAmount;

 // reverse the direction of the fading at the ends of the fade:
 if (brightness <= 0 || brightness >= 255) {
   fadeAmount = -fadeAmount;
 }
 // wait for 30 milliseconds to see the dimming effect
 delay(10);
 
 // Update all the buttons.  There should not be any long
 // delays in loop(), so this runs repetitively at a rate
 // faster than the buttons could be pressed and released.
 button0.update();
 button1.update();
 button2.update();
 button3.update();
 button4.update();
 button5.update();
 button6.update();

 // Check each button for "falling" edge.
 // falling = high (not pressed - voltage from pullup resistor)
 //           to low (pressed - button connects pin to ground)
 if (button0.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_PREV_TRACK);
   Keyboard.release(KEY_MEDIA_PREV_TRACK);
 }
 if (button1.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_PLAY_PAUSE);
   Keyboard.release(KEY_MEDIA_PLAY_PAUSE);
 }
 if (button2.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_NEXT_TRACK);
   Keyboard.release(KEY_MEDIA_NEXT_TRACK);
 }
 if (button3.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_VOLUME_DEC);
   Keyboard.release(KEY_MEDIA_VOLUME_DEC);
 }
 if (button4.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_VOLUME_INC);
   Keyboard.release(KEY_MEDIA_VOLUME_INC);
 }
 if (button5.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_MUTE);
   Keyboard.release(KEY_MEDIA_MUTE);
 }
 if (button6.fallingEdge()) {
   Keyboard.press(KEY_MEDIA_EJECT);
   delay(300);  // Mac OS-X will not recognize a very short eject press
   Keyboard.release(KEY_MEDIA_EJECT);

 }
}

(Use the code tags button, </> on the menu please. Thanks. Moderator)

What have you tried?

int volume

volume = analogRead(A0); // Potentiometer connected between 5V and Gnd, wiper to A00, result is 0-1023

Now do something with volume