How do I see what items I have ordered in the past?

You can find all of the items you have ordered along with their quantities in the Customer Center.

Go to "See Items Ordered" in the section called "Customer Center - Home Links". (see screenshot below)

This will take you to a page where you will see the product name, product description, the total amount you have spent on the product, the last date that product was ordered, and the total quantity ordered.