To edit your blog page, access it through the "Page Manager" (the first button of the PageBuilder's left toolbar).
Open "Customize Blog Article Page"
You can modify the layout of your page, and if you want to edit the article itself, double-click on it to access it's editing modal, and click on "Customize blog article details design".
A blog article on the left and a list of other articles on the right
The builder will open and display the layout of your article. You can add or remove elements to the layout by clicking the section "Blog articles component" found in the editing toolkit (paintbrush). You'll have the choice of binding elements such as the title, the date, the subtitle, the content, etc.
You can build absolutely anything. Your imagination is the limit.