Where is the lost treasure in the secret of monkey island

You need to buy the map first from the shady guy on the same screen as the three pirates and their rat. The map looks more like a set of dance steps, but it is actually the instructions to reach the treasure. When you enter the forest, look at the map and follow the steps - if the map says left, right, up, then it means go all the way to the left side of the screen onto the next, then all the way to the right, onto the next, then to use the exit at the top, etc.