Unfortunately, there is not a way to make the News tab the default home page for a Confluence space. If you want to configure a space to be a dedicated blog, you can simply use the {blog-posts} tag on your home page to show all blog entries. The home page for this space also uses the {popular-labels} tag to show the list of labels and their popularity which you see in the right hand column. Here's the full wiki markup for the labels tag. The heatmap style shows popularity using font size, the spaceKey is the shortname of your Confluence space, and the count is how many labels you want to show.
{popular-labels:style=heatmap|spaceKey=blog|count=10}
Here's another blog entry. Each time you click the Add News link it adds the new entry to the top of your page. Occasionally there is a several minute delay before the new entry appears on your home page. If this persists, quit and re-launch your web browser.
This is an example of a Confluence wiki set up specifically to be a blog (an online journal). The Confluence wiki supports blogging via the Add News link and News tab. You can also bring blog entries into any page with the blog-posts tag.
{blog-posts:5}
In addition, Confluence supports RSS feeds, so you can bring in RSS content from other websites and display it using the rss tag.
{rss:url=http://host.com/rss.xml|max=5}
Here's an example of RSS content.
Could not access the content at the URL because it is not from an allowed source.
http://www.realclimate.org/index.php/feed/atom/
You may contact your site administrator and request that this URL be added to the list of allowed sources.