There is no easy answer, as the method is slightly different for every device.
Find a subforum on XDA for your Note and go from there.
FWIW, I had to downgrade my Nexus 7 grouper because 5.0 was garbage on it. I found SlimKat based on 4.4 to be a very good ROM.
The gist of it though will be this:
1) Download a new ROM and an Open Gaps package and load it on your device via USB
2) Root your device and load TWRP onto it through Nexus Root Toolkit
3) Boot into TWRP to load and install your ROM and Open Gaps
Be sure to research specific instructions for your device though.