steps to flash custom ROM

[callmejoe9]

first time trying to root phone. still have some questions.
i have the sgh-i317.
i want to go from kit kat to marsmallow.
are these the right steps?

1. root phone - does phone have to be unlocked first or does CF autoroot take care of that?
- cf autoroot looks like it provides a stock recovery. from what i read i think i need something like the ClockworkMod recovery to flash a custom rom. is that right?
2. flash rom
does it matter which ROM?
i see 2 that are popular - cyanide and resurrection remix

thanks

 

[audit13]

No need to root the phone before installing a custom recovery.

I recommend TWRP over cwm as cwm is very outdated.

 

[callmejoe9]

seems the more reading i do the more confused i get. just trying not to brick my phone.

1. i've read that the bootloader needs to be unlocked in order to install custom roms. is that true? i cant seem to figure out if mine is locked or not
2. next i need to install a custom recovery like TWRP?
3. then the custom rom? like resurrection rom

do i need to be rooted for any of these steps to work?