1 ) If you want to import Drupal users to the CiviCRM contacts then go to :
and find link Synchronize Users to Contacts .
2 ) If you want to import CiviCRM contacts to Drupal users then :
a) Create a CiviCRM profile you want to use for creating CiviCRM contacts through any online contribution page.
b) In advance settings of this CiviCRM profile force users to have drupal account login.
c) To give a specific drupal role to these coming CiviCRM contacts in drupal , go to:
And find link CiviMember Roles Sync and add association rules as you want.