There are actually quite a few pieces to the blogging puzzle and you'll eventually need to know about all of them. Luckily, these days it's much easier to get going than it used to be. I remember when I first began blogging about 10 years ago, it was such a pain. I used Wordpress and had it installed on a server at a hosting company and the software was somewhat challenging to work with. These days, it's so much easier.
You have already thought of a domain name. Good. Buy it, even if you don't use it for some time. Through Google Domains, domain names only cost $12 for a .com. After that, you'll need to make sure you can do a few things. First, you'll need to make sure you can write. Even if you're no expert, you will need to get something down in your posts. People tend to become better writers as they begin blogging more, so don't sweat the fact that you might not be the greatest writer right now. As long as you're open to learning and continuously practicing, then you'll be just fine.
People love looking at photos in blog posts, so you should start getting used to taking pictures of lots of stuff. Each post you write is a story and photos go hand in hand with stories. I know people who never read anything written in blog posts. They only look at the pictures. To me, that's kind of sad, but each to his own, I suppose.
Think about what you want to write about. This is where people find the most difficulty. Each and every interest you have is a potential post. Every activity you engage in is a post. If you're into hiking, write about where the trail is, directions to get there, it's difficulty, photos of the area, video of the hiking itself. There is so much to write about. Are you learning photography? Write about that. Each question you ask Google should also be a post. If you're asking it, someone else is asking it too. Why not become a source for the answer? If you have any questions about content, please ask me. I have tons of suggestions.
Really, all you'll need from this point on is to decide on a blogging platform. Most people use WordPress. I mean, unless you're looking for something very specific, WordPress is pretty much a no-brainer. You'll just need to think about if you want to host the software yourself in your own hosting account or on the WordPress.com website. As a new blogger, I recommend you have it hosted with them. It's free in the beginning and if you start growing your site, you can always pay a few dollars a month to upgrade. You can also make it so your domain name points to your site pretty easily. So really, it's an easy process. If I were you, I'd go set a WordPress.com site up and start writing today. Be sure not to overthink things. The most important thing is to get going now. Too many people get stuck at each phase of blogging and never get off the ground. They find it intimidating. So many blogs fail before starting. Don't let this happen to you. Start blogging right now and keep going forever. Ask if you have questions.