make sure you install hplip-gui. That should get you an icon on the toolbar that you can use to right click and get the HP Device Manager. I believe the command line executable is hp-toolbox.
In the HP Device Manager or hp-toolbox, select the actions tab. If you have the fax setup and your all-in-one online, you should see a 'send fax' icon. Run that and you'll first decide whether to send a cover page, then add PDF files to fax, then select the destination fax, and then send.
It appears that 11.10 has a problem with some HP all-in-ones as the 'sudo hp-setup' routine doesn't enable the fax on some, like my 1522. This sort of regression seems to be too common a frustration to me but that is another topic. See
https://bugs.launchpad.net/ubuntu/+s...ip/+bug/790238 and
https://answers.launchpad.net/hplip/+questions?batch=75
I still miss the old OS/2 plus PMfax days. Efax or Hylafax with a fax modem attached to the machine can get close but the ease of setup and integration with the printing system just isn't quite as nice. Fortunately, the need to send or manage facsimile documents is almost gone these days.