Depending on your layout and other details there are a few ways to handle the display of the content from your related entity.
The most basic (and therefore limited) way is to go to Manage Display first on your article content type and adjust the settings for the format. It is likely already "rendered entity" (if not set that) and then click the gear to the right and set the view mode to be Default or Teaser. Once that's set, switch to manage the display of your authors and make sure the fields you want to display on your article pages are enabled.
The draw back to this approach is that it can have side effects unless you create extra view modes and are careful about when those modes are displayed. For example, if you change the teaser settings any place the author teasers appear will change to match. If you install Display Suite you will have additional options to control the layout of both content types within the Manage Display form.
A common approach is to use views. With Views you can create a block that displays the author information, and then you can carefully place that block where ever you need. There is a reasonably good tutorial on Drupal.org for how to set something like this up in a general case.
If you'd like to do more research on options I suggest searching for things like "drupal views entity reference" or "drupal ds entity reference".