The Fast Add (FA) detail mode can be used to quickly detail items to an order.
When using this mode, after you select a category you just need to click onto an item to bring up the detail drawer from the bottom of the page. Here you can choose to add further details about the item such as brand, and color, choose to add any up charges, or alterations. Once you're happy with the description of the item you just need to click anyways else on the page to save the item.
If you need to modify things such as the delivery date, or adding a coupon or discount to the order, this info can be accessed via the info tab in the top right hand corner. To make a change you'd select the edit button, make your change, and then click the save button.