There is no one right way or wrong way to lay out or set up an altar within your circle. Go with what feels right for you. Despite what anybody says Wicca is a free-thinking religion and is constantly changing.
This particular altar set-up is based on the premise of the altar being split into two halves with one half representing the Goddess and the other half representing the God.
Most Wiccan practitioners have the left – the western – side representing the Goddess but we know others who have the eastern side representing Her. Either is fine.
Additional items that you wish to use or place upon your altar should simply be split into their respective male/female correspondences.