Setting the dropdown to "Yes" means your posts will be sent to Twitter upon publishing. Before you do, you'll have to click the text link in the field's description (not shown in this screenshot because I've already done it) that takes you to the MODX Articles Twitter Authorization Page. At this page, login to the Twitter account you want to auto-post to, and voila! Your MODX blog is "connected".(on http://www.sepiariver.ca/blog/modx-web/modx-revolution-2.2-and-articles-blog-engine#!lightbox/2/ infact
)http://yourdomain.tld/assets/components/articles/twitter.auth.php?container=**