The object here is to place a snake, rhino, frog and tortoise in each horizontal and vertical row. The coloured animals around the outside are to show the first and second positioning from the side they are positioned on; green being 1st and blue 2nd. The other spaces are filled with water, some of which cannot be changed, as can't the occasional animal. Click on the squares to change them.

Hopefully the demonstration will help make things clearer.