To handle FBA orders you must have picking and packing queues. If you have all queues and received stock, FBA orders should be in state Assembling, if not, check your queues settings.
1. First thing you have to do is to pick all items for this order using Picking in Terminal
2. After that you have to pack all products using Packing
*(If you have more than one box to be send, system will ask you to scan products to different “places” and after packing will give you different labels)
3. Go to Workstation -> Labeling -> Start now
Scan labels that you get in Packing, set dimensions, and press enter, then wait until Amazon returns your FBA label.