You probably posted this in the wrong section, since I don't think the Kindle Fire HD's or the Kindle Fire 2 are running TWRP yet. Can you confirm that you are using the original kindle fire and not one of the three new ones that were just released?
If you do have the original kindle fire and it already has TWRP and FIRE FIRE FIRE on it all you need to do is download the rom you formerly had on your system, and the proper google applications for that rom and then flash them onto the device. The TWRP recovery software does have the ability to mount your device to a computer so once you've downloaded the rom and gapps you can simply copy it to the device (after checking the downloads with the md5 sum), do a factory reset, wipe the system, cache and dalvik and then install the rom followed by the gapps and reboot. Be careful and make a backup if you still have any important data on the tablet!
I have an original kindle fire running hashcode's rom which has been very stable and the only thing that doesn't work is the location capability (which for that tablet isn't important to me).
[ROM-AOSP] Stock Jelly Bean 4.1.2_r1 for the Kindle Fire [10-10] - xda-developers
If you have further questions or need more detail I can potentially do that when I'm home and have the table in front of me.