https://3ds.hacks.guide/
That's everything you need to know, complete with links to what you'll need. What you don't want to do is follow videos on YouTube, since the guide is the most up to date source on the subject. You can use YouTube videos to get an idea about it, but your primary source should be your number one source.
If you want the easiest method, you can get a card that comes flashed with ntrboot. Ace3DS X has it pre-flashed and are pretty easy to find, but a lot of them are clones and fairly cheaply made. There's also the new EZ-Flash Parallel Card, which is a more premium card but still pretty cheap. You can get them for around $25. Here's a link for the guide just for ntrboot cards:
https://3ds.hacks.guide/ntrboot