Hi Gouri,
Have you created any record for productorder and account and associated? When you create product associate to the account then you can see the entry in the table so the entry record will show the association between which product and which account.
Hope this helps.
A association between to entities describes an optional relationship between to instances of those entities.
In other words, you need to reference the order to the account.
You can associate a product to an account a) during creation of product or b) while editing your product.
To do a):
To do b)