first lets talk about the orders and order details relationship.
the orders table is where you store customer information.
the orderdetails table is where you store information about the products that where purchased as part of the order.
In the orders table, the primary key column orderID is used to create the relation to the orderdetails.DetailOrderID column
In the Store Oder Summary behavior, Make sure that the Order ID setting is set to the OrderID column, the "Store As" option is the name of a session variable that will contain the ID value of the record that is insert, make note of this.
In the Store Order Details behavior, Set the "Order ID" column to the detailsOrderID and bind that column to the session variable created by the Store Order Summary behavior.
In the store order summary behavior, bind the user columns like first name, last name to the checkout form elements.
In the Store Order details behavior, bind the product columns to the appropriate columns from the eCart object.
the store orders details behavior will create a record for each row in the cart display.