WordPress.org

• Upload privatepost.php to your 'wordpress/wp-content/plugins'
• Enable the plugin in your admin section
• Go to 'Options > PrivatePost' and select the category which contains your "Private Posts" (Optional)
• Set your "Private" indicator (Can be txt or image)
• Set your Private RSS feed (This is updated anytime a post is made public). Make sure it is writable by your server.
• Add it to your sidebar

That's it you're done!