To write a blog post, you can use the WordPress Block Editor or the Divi Builder. The Block Editor is recommended for writing your blog posts; you can build it “block by block” and easily manage settings, and your finished post will automatically appear on your blog page – no formatting or design needed!
The Divi Builder is really more for highly customized blog posts; I recommend using the block editor, but I’ve included a link below on using Divi Builder for blogging..
To add a new post, go to your WordPress dashboard and click on Posts > Add New. From here, choose the editor you’d like to use. Add images, text, and links; set a featured image, excerpt, category, tags, slug and more. For details, see the following articles:
Block editor: https://wordpress.org/documentation/article/wordpress-block-editor/
Posting with the Divi builder: https://www.elegantthemes.com/blog/wordpress/how-to-create-a-wordpress-blog
Blogging Overview: https://www.elegantthemes.com/blog/business/how-to-start-a-blog
Note: there are a million resources out there on blogging best practices, SEO tips, good writing, blogging as marketing, and more. You can go as simple or as deep as you want!