Clockwise from the top, the eight sectors of the Feng shiu bagou is fame, relationships, children, helpful people, career, knowledge, family and wealth. They are set around the yin-yang which symbolises the life force generated by opposite or contrary forces in nature and overall well-being. The yin-yang can also be related to evolution though mutation and natural selection if you want to get very philosophical.
Just because the Bagua is an octagon, it does not mean that your garden has to be an octagon. Just adhere to the directional placement of each sector as indicated on the figure so that each sector is associated with a direction. The design of your feng shui garden is something personal because it should resonate with your emotions, taste, memories and spirit. So we will discuss how we would design our perfect feng shui garden, but remember that it should be customised according to what you associate each sector with.