How to create an article sharing site?
Because you are very inexperienced with Drupal, you don't know that your question is actually a set of several questions.

If you never have used Drupal before, you must understand a few basic things about Drupal, then learn about how to install it, and how to administrate (and customize) your Drupal to add the features that you want.

Also, Drupal has installation profiles; there are a variety of "pre-configured" versions of Drupal you can download and use for common needs. I am not sure any profile exists that is specialized for your needs, but you can search and select the most suitable and customize according your needs.

Update: 
If you have installed a Drupal version, and have reviewed the basics of Drupal administration, you can find and test several options for modules to (integrate with Facebook](http://drupal.org/search/apachesolr_multisitesearch/facebook%20Integration?filters=ss_meta_type%3Amodule). For letting people share their content, you can review that with Content Types and CCK fields (CCK is needed for Drupal 6) you can create separated types of content having custom fields according your needs.

here http://drupal.org/documentation/modules/field-ui and here http://drupal.org/node/774728 are documentation about how to create a Content Type, and here is screenshot about where you can add custom fields for Content Types:



Remember review Drupal profiles, can be a suitable answer that you can customize with content types and Facebook integration.