General steps are: Gain root access, install custom recovery (these might be flipped around), make a backup through recovery, use the custom recovery to install the ROM.
The real questions are: Is there a recovery for your EXACT device, and is there a ROM for your EXACT device? Close is not good enough. If you install a custom recovery on a device that it isn't made for you could possibly brick it.
I would suggest getting a cheap/older Samsung device and practice with that. The last thing you want to do is brick you daily driver.