The OS updates get pushed out shortly after release, but I think they stop pushing after a few months. To get them you have to leave the wireless turned on, though the device can be in sleep mode.
If you've not gotten it, you can do it manually but it generally requires access to a computer. You have to download the file from the help page on Amazon and then copy it to your device and run it. Don't think a mobile device would work because you have to be able to physically connect the Fire as a drive. I don't know if you can download it to the Fire and then use a file management app to put it in the right place on the device so that the update will run.
You might try calling Kindle/Fire customer support and telling them you never got the update, explain how you don't have a computer, and see if they will push it to you.
Having a way to grab it via the MYC&D (Manage Your Content and Devices) page would be a good thing, but that's never been how you do it manually. Still, I think I'll make that suggestion to the Zon!