Hi Anton,
Out of the box, drupal supports 2 basic roles: registered users and anonymous (basically logged in and logged off).
You can find some more details on how to leverage them here:
Another option would be to use drupal modules to expand on the portal capabilities and configure full blown RBAC access into the portal. More details on this options is available here: http://docs.apigee.com/developer-services/content/managing-role-based-access-content-your-developer-portal
I hope this helps,
Ricardo