How to Duplicate Barcodes: No PC or Mobile Device Needed

So you bought barcoding hardware (a scanner and printer); now what?
Scenario
A user buys barcoding hardware (a scanner, a label printer, and maybe even a cart or other equipment) but now he can’t figure out how to duplicate the barcode that he just scanned. Whoever sold him the hardware told them they can print labels. But what he was not told is that he will need software to do it.