If you ever need to publish your article as a draft to your blog, you will need to set your article to Draft status first before publishing. To set your article to Draft status, you may either set it inside your Blog Editor, via Review->Draft button as shown below,
or you may set it by right clicking on the desired article via Article view in the main window, and set it from the popup menu that appears.
After setting the Draft status to the desired article, you may proceed with your publishing using the blog writer as usual.
Should you want to publish your article as normal post later, do remember to unset the Draft status and publish again.