Arduino/programming

hello i need help controlling my processing document with arduino controls. the processing document is a 3D etch a sketch, below is the processing code :

import processing.opengl.*;
int x, y, z;
int speed = 10;
//PImage etch;
void setup() {
size(900, 630, OPENGL);
background(255, 255, 255);
}
void draw() {
// background(255, 255, 255);
lights();
pushMatrix();
translate(width/2, height/2);
noFill();
box(450);
translate(width/12, height/12);
translate(x, y, z);
strokeWeight(2);
stroke(128);
sphere(5);
strokeWeight(2);
stroke(5);
noFill();
smooth();
strokeWeight(10.0);
strokeJoin(MITER);
beginShape();
vertex(35, 20);
vertex(65, 50);
vertex(35, 80);
//endShape();
popMatrix();
}
void keyPressed() {
if (keyCode == UP) {
y-=speed;
}
if (keyCode == DOWN) {
y+=speed;
}
if (keyCode == LEFT) {
x-=speed;
}
if (keyCode == RIGHT) {
x+=speed;
}
if (keyCode == SHIFT) {
z+=speed;
}
if (keyCode == CONTROL) {
z-=speed;
}
}

so there question is how do i make the arduino control the etch a sketch / please help

The Arduino communicates with the PC via Serial comms. Processing has the ability to read and write Serial data. Base your actions off serial data coming from the Arduino instead of keystrokes from the PC.