Hi! I'm Eric, a Mac expert who's been paired with you through JustAnswer.com. I'm reviewing your question now, and will return w/ an answer soon!
Would you please tell me: do you have other devices on your network that are able to print to this printer?
Also, were you attempting to set it up using the built-in printer software available on your Mac, or had you downloaded/installed the official software driver available from HP (http://ftp.hp.com/pub/softlib/software13/COL31995/mp-109977-3/OJ_AIO_J6400_Full_Win_WW_140_408-5.exe)?
Thanks for the additional information. I look forward to hearing back from you and helping you resolve this problem!