1. Go to https://ecommerce.apple.com/ and Log In
  2. Go to the three horizontal bars in the upper right and select Proposals
  3. Click the blue Convert button on the order you want to place
  4. Select the blue Checkout button 
  5. Fill out the shipping and payment details and scroll to the bottom and click on Verify Order
  6. Review the details one last time and if correct click the blue Place Order button
  7. That's it! There is an option at this screen to download this order as PDF if you need those records as well.