How do I set up faxing on my HP OfficeJet Pro 8720?

You can set up fax through the HP printer software or the printer control panel. For Windows users, open the HP printer software, go to the Fax tab, and select the Fax Setup Wizard. For OS X users, use the HP Utility Service software after software installation. On the control panel, touch Fax on the home screen and then touch Settings. (Page 2)