Using arrays to create a node and edge connector

Processing Coding Questions
7

ok so ive manged to store each of the positions of the balls and made it abit more simpler but now im stuck with making each ball connect to every other ball with a straight line. what should i do?

int length = 101;
PVector[] position = new PVector[length];
int BallNum;

void setup() {
  size(600, 600);
  background(255);
}

void draw() {
  fill(255);
  layout();
  fill(0);
}

void mousePressed()
{
  BallNum++;
  position[BallNum]= new PVector(mouseX, mouseY);
  circle(position[BallNum].x, position[BallNum].y, 20);
  if (BallNum >= 2) {
    //line(position[BallNum].x,position[BallNum].y,position[BallNum+1].x,position[BallNum+1].y);
  }
}

void layout() {
  for (int yLine=0; yLine<=width; yLine+=width/10) {
    for (int xLine=0; xLine<=height; xLine+=height/10) {  
      line(yLine, 0, yLine, height);
      line(0, xLine, width, xLine);
    }
  }
}