Better idea maybe to just create a component / template with the required layout and dialog fields to compose the blog posts. Then just create a new page using that template whenever you want a new blog post.
This is assuming you want an approach to create blog posts rather than a component to list down existing blog articles. It's not very clear from your post.
If you're talking about allowing end users to create blogs on publish instance then CFs may not be used since they're an author-only feather AFAIK.
Content Fragments are simply a collection of text and style. To build what you are describing, you will require a more complex set of components. You can look at using existing components or build your own components using Java and Sling Models.