These are the default steps that you need to do in order to add a blog post:
1. Go to Posts > Add New
2. Enter a title and some content.
3. Select a post category.
4. Add some relevant tags.
5. Add a featured image. Size (and aspect ratio) should be based on the blog style that you choose:
- Modern style - use a large 16:9 image, like 1920x1080px
- Classic style - use a large 4:3 image, perfect size is 1536x1160px
Don't worry about large images, the theme will automatically do resizing and display the proper image for each user.
6. Insert all of your remaining content in the content area. You can have images, paragraphs, etc..
7. Write a few words excerpt (it is good for search results and SEO to have an excerpt, no matter what kind of content do you have in your post).
8. Hit “Publish” and you’re all done.