Hi I don't mind helping you out friend
We were all new to this at some point, so remember to always ask for help if needed most of the time someone will tell you what you need to know or point you in the right direction.
Will go thru what I personally think is easiest way to do what you want.
OK so your already rooted that's a great start.
Next, go to the playstore and download an app called "flashify" get that installed and run it.
select from the menu "recovery image" and then select "download TWRP" it will take you to a list of devices find the one for your note 4 which I assume is the Exynos version. Click on that select the latest version and it will download it for you and prompt you to flash the recovery, if you say Yup it will run the flash for you.
That's it you have your phone running TWRP
to get into the recovery (personal easiest method again) go back to playstore and search for an app called simply "reboot recovery" Install that also and and start it and it will boot you into recovery\twrp from there you will see options such as install, wipe, back up and restore.
First things first hit backup and run that (always best to have a fall back before you start to play around).
After that your good to install any rom for your device simply be going into TWRP going to wipe (it will tell you the most common type of wipe in the menu and you're probably best off sticking with that for now) after the wipe hit install flash your chosen rom from your sd card and swipe to flash it. After flashing it will ask if you want to wipe cache & dalvic which you do want to unless told otherwise. Then reboot system and enjoy your new rom.
Hope that helps please quote me in this thread if you need more help and I'll do my best to assist you and of you quote me I'll get an email to let me know
Best of luck
