Label Printing
Before you attempt to print barcode labels you need to tell Commander4j what type of printers you are planning to use.
There are 2 types available.
Zebra Compatible (ZPL) Printers
If you are planning on using Zebra compatible printers then you will need to ensure that your print queues are setup correctly.
I would recommend the documentation provided by the excellent JZebra project here
Laser Printers
No special configuration required for these printers - just install the appropriate driver. Do remember however that the quality of a barcode printed on a standard printer will not be as good as a purpose built barcode printer.