Like pages, blog posts are now added to your space by clicking the "Create" button at the top of the page. Blogs are also now more exposed in the Wiki navigation, making your posts more visibile and easier to find.
If you are ready to add a blog post to your space, click the "Create" button on the toolbar at the top of the page. After selecting the space, select blog post as the content type and click the "Create" button. You'll then be taken directly to the Confluence Editor so that you can add your blog post.