Many people use online faxing companies or fax capability from their personal printers. However you need to be hooked to your printer to send faxes from your computer be it laptop or desktop.
you can send a fax wireless through AirPrint or wireless network printers via the printers software installed on that device. However yet again you still need a software program to compose the document, programs like Microsoft Word or Corel WordPerfect can be fax from the desktop. You can google the process from