You can use the shopping cart if you are trying to place an order with several different books that you've created in your account. Here are the steps on how to use the shopping cart.
1) Make sure that all of your print ready files have been created and are up to date for all of the books that you would like to order.
2) Begin the checkout process by clicking on the Shopping Cart Icon associated with one of the books you would like to order.
3) Input the quantities of each binding style that you would like to order and then click on Add To Cart. You will be taken to Step 1 of the checkout process.
4) Click on the CreateMyCookbook logo in the top left corner to return to your "My Cookbooks" page.
5) Click on another shopping cart icon associated with another book that you would like to order to access another book's checkout page.
6) Add a new quantity of books to your cart.
7) Keep repeating until you've finished adding all the books to your shopping cart. Once your cart has all of the books you want to order in it, proceed with checking out.
Here's a quick video tutorial for placing an order with different books: https://youtu.be/nrBT8zI3sP8.