Note: you will probably need an archive manager like winrar or 7zip (if on windows, idk what you will need on mac, linux should be fine though) to extract the files for
Setting up a bootmanager for menuhax and homebrew (so you can use homebrew and cfw automatically if you have not) (The next steps assume that you do not just use the normal homebrew launcher to boot cfw, if you do, you can skip this if you want)
0a. If you are using a boot manager (i dont remember the name of it, but it has a purple screen last time i used it) you should have a file called boot.cfg in the root of your sd card. This will be replaced later, but if you do see this, skip to step 1, if not...
0b. You may be using rxtools.3dsx as the boot.3dsx (you will likely boot right into rxtools if you hold select). You will want to switch over to a boot manager. (So you have access to cfw booting and homebrew when you need it)
0c. If you are using the homebrew launcher, and it is up to date or the grid launcher, rename it to boot_hb.3dsx to save a step
1. Download the file at the bottom of the first post from here:
https://gbatemp.net/threads/ctrbootmanager-3ds-boot-manager-loader-homemenuhax.398383/
2. Drag both files to the root of your sd card, let everything overwrite
3. Open the boot.cfg and change everything called Reinand to Luma3ds. Leave everything else alone.
4. Download the latest homebrew launcher, rename it to boot_hb.3dsx and put it in the root of your sd card
Setting up luma
1. Delete the rxtools folder, the rxtools folder in /3ds/ and rxtools.dat
2. Download the latest release of luma3ds from here:
https://github.com/AuroraWright/Luma3DS/releases (don't download dev unless you actually need it for something (you most likely do not)
3. Drag the 3ds folder, luma folder, and luma3DS.dat (all in the download) to the root of your sd card
4. Turn your ds on and see if everything is working fine. You should have a 3 second boot time, you can change this in the cfg or "more... > settings > timeout" use left and right to change it
5. If you do not forget to copy files over (like me

) then you should see Luma3ds v5.5-something configuration. Go ahead and setup what you want on there (do not check autoboot sysnand)
6. Press start and you should be good to go
If I forgot something, or are confused, let me know where you are at and I will try to clarify it.