If you don't have twrp recovery in your device you can follow this link to install TWRP recovery in your Fire Tab 7.
Warning: We gammerson.com is not responsible if you damage or brick your device. Do it at your own risk and follow the instructions properly.
How to Flash Cm12.1 Rom on Fire Tab 7 2015
1.After completing the above steps Download Cm12.1 Rom from last of the post and Gapps for android 5.1.1 for Cm12.1.
2.Then place it on your SD card on you tab 7.
3.Now turn off Fire Tab 7 and turn ON by pressing Power button +Volume Down button to boot into recovery mode.
4.Now Press volume down button to highlight Recovery option on Bootloader then press the Power button to Select it.
5.Now your device will boot into TWRP recovery.
(Note:Before you flash Cm12.1 in your device make backup of current rom in case anything wrong happens so that you can recover it).
Now tap on install Button and then select SD card and select the CM12.1 rom .zip file that you placed on your SD card.
6.Swipe below arrow to flash Cm12.1 rom, in your device and then similarly flash 5.1 GAPPS in it.
7.Now go back yo recovery Home then do Clear cache, Clear Dalvik cache.
8. Now reboot your device.First boot will take some time after few min Cm12.1 will be installed in your device.
9.Done!You have successfully flash Cm12.1 Rom.
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