WordPress.org

Download a Private Only package file, extract a private-only directory from ZIP file, upload it to WordPress Plugins directory '/wp-content/plugins/' Visit this page, http://pixert.com/tips-and-trick-on-how-to-use-private-only-plugin-with-prologue-theme/ for Prologue theme users

Visit WordPress admin area and activate the plugin If you are new to WordPress : http://codex.wordpress.org/ManagingPlugins#InstallingPlugins