If you want to view what's in your order during your customization window all you need to do is click the pink Customize button on your account page. Once your customization window has closed for an order you can find the list on your order invoice on the Billing Details page of your account.
To view your order invoice:
Step 1: Go to "Billing Details" under the "My Account" menu.
Step 2: Scroll down to the "Billing History" section.
Step 3: Click the grey "View Order" button for the order you'd like to review.
Step 4: This will open up your order invoice to you to review the contents of the box as well as the order total.