If by "stock", you mean its never been hacked before, start here:
Double check your exact version. The best case is you can use Soundhax.
If not, get a compatible card for NTRBoot.
Do I need to do the "To use NTR CFW, install BootNTR Selector." at the bottom of finalizing-setup page? last page of soundhax called Finalizing Setup....cant post links
Only if you want to use NTR (used for cheats, and streaming your screen in N3DS).Do I need to do the "To use NTR CFW, install BootNTR Selector." at the bottom of finalizing-setup page? last page of soundhax called Finalizing Setup....cant post links