As soon as you figure out what and how to write, you need to publish what you have written. You have many options. Start with a standalone blog.
You can post your writing on social media sites. Those sites have huge audiences, most of the people you want to reach are already there, you just sign in and start writing, and it is “free”. But you give up all your rights at the moment of posting. You give up your content and your audience from the beginning. You have no control over page URLs, which makes it hard to transfer your content out of the platform. Your posts may be censored and your account can be banned. You cannot know which of your posts will appear in your followers' feeds. You do not decide how your pages look. You cannot remove ads, or change colors or fonts. When a platform dies, all your hard work disappears. You do not own your blog.
A slightly better option is to use one of the blogging platforms: Medium, Svbtle, Tumblr, WordPress, etc. You have control over your page content. You can set up a custom domain and have some control over page URLs. But you are tied to a platform and its software — it’s painful to transfer your content out.
What does it mean to own your website? You need to fully control your domain, your content (rights, URLs, styles, markup, etc) the communication channels to your readers (emails and comments).
So if you’re serious about blogging, should you make everything from scratch? Fortunately, you don’t have to create the universe to make your own website.
Try GitHub Pages.