A: AST user ID and password: Fill out your user ID and password when you used to connect your MWS account with ASellerTool.
B: Amazon seller id: If you are US seller, use ATVPDKIKX0DER as MarketPlace ID. You can find your seller account id here.
C: Fulfillment Channel: Choose whether you want to list the following items as FBA or MF. You can switch between them. Ex. If it is set to FBA currently , but you want to list next items as MF. You can change it to MF, then start to list those items. After you finish, you can change it back to FBA.
D: Box Content (FBA only): If you ship everything in one box, you ca skip it. If you ship multiple boxes in a shipment, Amazon requires you to provide box content information for each box. You can choose to use 2D barcode to show box content.
E: Ship-from address (FBA only): Specify the address where you ship your FBA items from.
F: Transfer Between Computers: If you install this software in a new computer, you can Export your settings and current work from current computer into a file, and Import that file into your new computer.