A blob relies on server-side software and a database, typically PHP and MySQL. SiteSpinner can only be used to create static websites, so it cannot support the dynamic pages required for a blog.
That being said, there are ways to use SiteSpinner to build a WordPress theme and then use this theme in a WordPress site. This is not easy and you need knowledge how how to build a WordPress theme and some knowledge of PHP and MySQL.
If you are an advanced user and are really knowledgeable in PHP and MySQL, there are ways to use the WordPress API directly within SiteSpinner. My own site is built this way.
For a community forum like the one VM uses, see if your hosting service provides a phpBBS package you can install. This is a popular bulletin board / forum package. While you cannot use this directly within SiteSpinner you can always provide a link to & from your main site to your forum.