what you need:

Ardunio uno
2 potentiometers

applications needed:
Ardunio
Processing

Step 1:

1: Download the Ardunio library for Processing, unzip file

2: Go to your "Sketches" directory, the default is ...Documents/Processing

3: Create a new folder if not present called "libraries"

4: Move the unziped directory ("arduino") into "libraries"

5: Quit Processing

6: Prepare your Arduino & breadboard with a two potentiometers with one wipe going to A0 and the other to A1

7: With your Arduino connected open the Arduino IDE, and load the script from Examples / Firmata / StandardFirmata

8: Upload that sketch to your Arduino

9: Open Processing IDE and use the following sketch (Note: I commented out my image background)

Step 2: Schematic

skematic.pdf
Download

Step 3: Processing Code

import processing.serial.*;
import cc.arduino.*;
Arduino arduino;

void setup() {
size(1600, 800);
// background(b);
background(17, 44, 84);

fill(255,0,0);
noStroke();

arduino = new Arduino(this, Arduino.list()[4], 57600);
for (int i = 0; i <= 13; i++){
     arduino.pinMode(i, Arduino.INPUT);
}

}

void draw() {

    int a0 = arduino.analogRead(0);
    int a1 = arduino.analogRead(1);

    ellipse(a0, a1,10,10);
}