If you see a pink ball inside a black square to the right, that means Java is installed and Jmol works. (The first time it may take a while.)
  If the ball turns green and gets smaller when you click the link "small & green" (below the black square), your configuration of operating system, browser and Java is correct for this tutorial.
(There may be a slight delay too in responding to the first use of a link or control button.)
  Clicking the button labeled "large & pink" should restore the pink color and larger size.
  Choosing one of the "blue", "red", "yellow" radio buttons should change color of the ball accordingly.

  If there is no black square, no pink ball, or it does not change when you click on the link, button or radio buttons, visit this page to obtain information on browser compatibility.