The first step would be just to do it, right? The way you begin is to just begin. Then you improve from there.
For instance, try this: find your favorite YouTube channel of somebody teaching music theory or performing song covers. Whatever you imagine yourself doing, consider what channel would be your prototype. What do you aspire to be? Now, go their their "videos" tab and "sort by date" so that you are seeing their oldest video that they uploaded.
It's probably abysmal isn't it? Poorly lit, low quality camera, bad sound, unedited, and they are probably rambling a bit.
I think a great example is Adam Neely. He's got a very popular channel with over a million subscribers. But if you go back to his first video, it's just a blurry performance of him performing "Maple Leaf Rag" in what seems to be his childhood bedroom in sweatpants. And not that it's not a great performance. It's just not really what his channel is about these days.
Now that was around the start of YouTube, and I'm not saying that it's going to take you 15 years to succeed. But if you look at any successful YouTuber, they started somewhere and built from there. You'll learn as you go and put more money and effort into your setup as you can afford to, but none of that can happen unless you just start.
As for tools, I'd probably start as simply as possible using just YouTube and add other tools as needed. OBS is free and probably useful if you need to record video/audio from your screen and not just your webcam.
It also depends on what you want to record. Guitar is easy enough because you just have to sit in front of the webcam. But piano is a bit harder because people kind of expect an overhead view of the keys. So just make sure people can see what you're doing at minimum and then put more effort and money into it as you can afford to.