Installing custom rom
1. Reboot to TWRP recovery and see what version is installed, should be 22.214.171.124 or higher. If you have older version you will need to up date.
Watch first 2 mins of video posted below to see how to reboot to TWRP.
2. Pick a rom, latest android version is KitKat/ 4.4 some KitKat roms are Cm11, CM11.0/SGT7, SlimKat PAC-man
They are all similar, features will very a little. I can't say which one will work best for you, I'm currently using SlimKat. but Cm11 is a good rom to start with.
3. Download Rom and Gapps (Google Apps). Don't download 'OtterX' roms unless you follow the Project OtterX instructions.
KitKat Gapps: 20140105
4. Verify MD5 checksum for rom and gapps MD5 is posted on Rom/Gapps download pages.
see how to use checksum https://sites.google.com/site/sdshad...hash-checksums
5. Install rom and gapps in twrp recovery see how to install a rom on Kindle Fire it's an older rom but steps are the same.
XDA really rocks.