You can view an order by clicking on it in the My Orders window:
Your order will appear in the View Order window to the right.
You can change the text of your PO#/Note by clicking on it.
Similarly for the Order Date:
And each item's Quantity:
To remove an item from your order, click on the at the end of its line. Your item will be moved to the Cancelled Items list at the bottom of the order. You can put your item back by selecting it from this list.
You can add a new item to your order by typing part of a plant name into the New: field at the bottom of the order.
After selecting your plant, the per plant price will be listed at the end of the line. Enter your quantity in the box provided and hit <Enter> or click on Add Item