Order Value per Region

[yrstruly]

Please assist. I would like to answer this question: "What is the average order value in the African Region per month?"

My Data Model:

 

My Code:

 

SELECT Avg(Orders)  AS Order Value

FROM Orders, Customer, Nation, Region

Join Customer AS C

ON Customer.Custkey = Orders.Custkey

Join Customer AS C ON Customer.Nationkey=Nation.Nationkey

Join Nation.Nationkey=Region.Nationkey

 

where Region = Africa