Query tuning

Hi Gurus,

I am relatively new to tuning, i ha ve a sql query running in the database which along with its execution plan is as follows

SELECT   addss.line1 addss_line1,   addss.pcode addss_pcode,   addss.suburb
addss_suburb,   addss.state_code addss_state_code,
NVL(roles.end_dttm,TO_DATE('31/12/2099', 'DD/MM/YYYY')) roles_end_dttm,
roles.start_dttm roles_start_dttm,   roles.patnt_refno refno,   roles.patnt_refno
perca_patient_refno,   roles.emplr_refno emplr_refno,   roles.secure_flag
roles_secure_flag  FROM address_roles roles,   addresses addss  WHERE
addss.addss_refno = roles.addss_refno  AND roles.rotyp_code = :1  AND