Please I need help with the question below:

--3.Find average sales (Total Due column) for each sales person ID. Select top 3 sales persons with the greatest amount of sales

This is my code:

select Top 3 SalesPersonID as 'top 3 sales person ID', count(SalesPersonID) as 'average sales'

from Sales.SalesOrderHeader

Group by SalesPersonID

order by 'average sales' DESC;