When I create new article I don't see the preview button.

Unfortunately in the current system previewing a new page article is not possible because the article does not yet exist in the database.  

There is a method that we use when we create new articles on a live site. We simply create the new article on your "sandbox" page. Save it there and if it meets your desires, then simply reload the artical and change the display page from your "sandbox" page to the actual page upon which you wish it to appear.  Make sure you have the ranking set to the order you wish it to appear on the final page.