Main Body
SELECT
Customer.[Customer ID]
,Customer.[Customer Name]
,Customer.[Last Year's Sales]
,Customer.City
,Customer.Region
,Customer.Country
,Orders.[Order Amount]
,Orders.[Customer ID]
,Orders.[Order Date]
FROM
Customer
INNER JOIN Orders ON Customer.[Customer ID] = Orders.[Customer ID]
WHERE
Customer.[Last Year's Sales]>0
ORDER BY
SUM(Customer.[Last Year's Sales],Customer.Country) -- Top N Order
,SUM(Customer.[Last Year's Sales],Customer.Region) -- Top N Order
,Customer.City ASC -- Group #3
,Customer.[Customer Name] ASC -- Group #4
,Orders.[Order Date] ASC