To attach the responsibility through backend

select * from fnd_responsibility_tl
where responsibility_name like 'System%Admin%';

select * from fnd_user
where user_name like 'ElangovanRagavan%'

/* Formatted on 4/15/2013 2:29:09 PM (QP5 v5.114.809.3010) */
BEGIN
   fnd_user_resp_groups_api.insert_assignment (
      user_id                              => 1338,           -- fnd_user -- USER_NAME
      responsibility_id                => 50922,          -- fnd_responsibility_tl  -- RESPONSIBILITY_ID
      responsibility_application_id   => 200,         -- fnd_responsibility_tl     -- APPLICATION_ID
      security_group_id               => 0,
      start_date                         => SYSDATE - 1,
      end_date                          => NULL,
      description                       => ' '
   );

   COMMIT;
END;

Update Responsibility

/* Formatted on 4/15/2013 2:29:09 PM (QP5 v5.114.809.3010) */
BEGIN
   fnd_user_resp_groups_api.Update_assignment (
      user_id                              => 1013855,           -- fnd_user -- USER_NAME
      responsibility_id                => 50578,          -- fnd_responsibility_tl  -- RESPONSIBILITY_ID
      responsibility_application_id   => 201,         -- fnd_responsibility_tl     -- APPLICATION_ID
      security_group_id               => 0,
      start_date                         => SYSDATE - 1,
      end_date                          => NULL,
      description                       => ' '
   );

   COMMIT;
END;