To play you click on the character and they cast their fishing rod. Wait for a while and you'll start to hear some noise and see the fishing rod move. To successfully fish you need to wait till a different audio cue happens and the icon of the mouse has one button turn black. There are also some things like flowers, mushrooms, leaves, and spikes that you can place with the bones on the gray patch of mud. I personally love decorating the bones or laying the bones on these materials.