You're obviously very confused, and I think the best course of action is to go through some tutorials to improve your understanding.

If you follow some working code with explanations for a while, perhaps it will make more sense.

If you don't understand that you need to use "if (...)" or something similar to change the behaviour of the draw() method based on some condition (such as the mouse being pressed), you will not likely understand the solution. So far you are having trouble just explaining what you want.

if (mousePressed) { ... } means do the part inside the curly brackets if the mouse is pressed. mousePressed is a BOOLEAN VARIABLE, with value true or false. The void mousePressed() method has the same name but is a different thing - it gets CALLED when the mouse is pressed, and inside that method you are setting some LOCATION variables, but not keeping track of whether the mouse is CURRENTLY PRESSED or not. The mousePressed variable keeps track of this for you, so what you need to do is write, as I showed you before:

Code:

draw()
{
  // The circle drawn whether the mouse is pressed or not
  ellipse(x1, y1, size1, size1);

  if (mousePressed)
  {
    // The circle which only appears when the mouse is pressed
    ellipse(x2, y2, size2, size2);
  }
} 

If this does not make sense, please do not ask again until you have done some tutorials. You won't learn anything thrashing around without some basic ideas to start you off.

-spxl