Win points for every correct piece and lose points for any pieces you try and place in the wrong place. Every minute of play reduces your score, as does clicking the show picture button. Your final total can be added to a high score table if you wish. Or just totally ignore the points and make the jigsaw in your own time. Use the pass button at no cost in points to move through the available pieces one by one. Left click and drag each piece, if you think you know where it fits, and drop it into place. A tip is to find the corners first and then the edge pieces.