paolaExample

Particle[] particles = new Particle[10]; // an array of objects from the Particle class

void setup() {
  size(500, 500);
  for (int i=0; i<particles.length; i++) {
    float x = i*50; // based on your example
    float y = i*20; // I made something up
    particles[i] = new Particle(x,y); // create new objects of the Particle kind
  }
}

void draw() {
  background(255);
  for (int i=0; i<particles.length; i++) {
    particles[i].paint();  // draw the Particle objects
  }
}

class Particle {

  float x, y;
  float sz = 10;

  Particle(float _x, float _y) {
    x = _x;
    y = _y;
  }

  void paint() {
    ellipse(x, y, sz, sz);
  }
}