boolean title = true;
void setup() {
  size(600, 600);
}
void draw() {
  if (title) {
    textSize(50);
    text("this is the title screen", 50, 300);
    textSize(10);
    text("Press enter to start", 200, 400);
    if (keyCode == ENTER) {
      title = false;
    }
  } else {
    //insert your code here
    background(0, 0, 255);
  }
}