My phone is rooted and I have the TWRP installed. I am not sure where to go from here though.
If there isn't either an official or unofficial port, you can't, and don't try to with a version that has not been specifically been made for your device. I'd recommend installing plain Android (with or without Gapps, as you wish) and wait for someone to do the port. Developers tend to port Cyanogenmod to the device they have if there is no port so far.
Of course, you could do the work yourself, but I don't think you want to do that because it involves messing with the core software of your phone and you need much experience in quite a few programming languages to make a port yourself.
There are likely sources to build CyanogenMod from scratch. I did find the forums at xda helpful http://forum.xda-developers.com/t/samsung-galaxy-on5 I wouldn't be suprised if you see CM 13 or 14 in the near future. If you are on a linux box you could possibly build from scratch.