It's not as simple as that:
SELECT TOP 10 * FROM myTable
Will return you the first ten items in the table, but only you can decide what makes them the ones you want. You probably want some combination of
WHERE
clause (to ensure that the month is correct) and
ORDER BY
clause (to organise them properly).
But only you know what makes a product "top ten". Is it number of units? Total value? Units per salesman? Or what.
Try it in SQL Server Managment Studio. and see what you get...