fmOrdersManage, fmProductsSearch, fmOrderProductOptions - Order Details Management
Here you can manage the list of products of the selected order, discount, shipping and taxes information. At the bottom you can see order totals section that shows you subtotal, discount, tax and total values.
In order to add new product to the order:
To remove a product from the order just select it and press "Delete" button .
An option is basically a specific value of some product attribute, so by changing product options you're changing an ordered product.
To Edit product options: