You need to install the addon first.

For 2.79 Go to File > User Preferences > Add-ons and click the button in my screenshot and point the dialog box to the .zip file

[![enter image description here][1]][1]


For 2.8 Go to Edit > Preferences > Add-ons and click the same button and point the dialog box to the .zip file


[![enter image description here][2]][2]

Then you can go to File > Import and you should be able to import your desired file type.


  [1]: https://i.sstatic.net/ibDkp.jpg
  [2]: https://i.sstatic.net/bIEGJ.jpg