How do I enable the USB port for printing from a USB flash drive?

The USB port must be enabled before printing from a USB flash drive. You can enable the high-speed USB 2.0 port either from the printer control panel menus (Method one) or from the HP Embedded Web Server for network-connected printers (Method two). Once enabled, you can use the easy-access USB port located on the front of the printer to print and scan without a computer. (Page 47-48)