Some people write GitHub gists as that's the simplest possible way to do it, probably (or the equivalent on BitBucket/GitLab etc) and it's pretty decent with good support for code samples.

Otherwise, if you want to start a real blog, I recommend a static site generator[1] and one of the free services like Netlify, GitHub Pages or Cloudflare (which has free, cool domains like your-name.pages.dev).

[1] https://jamstack.org/generators/