Retreive Username making update [Oracle Apps]

 I been trying to write a trigger to capture audit for upadates being performed

on a table.  I can't quite figure how how to know who is perfroming the update.

My code so far is :

CREATE OR REPLACE TRIGGER APPS.NEW_EMP_VER_ADDv2
BEFORE UPDATE
ON HR.PER_ADDRESSES
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
DECLARE
   --CH_DATE DATE;
   UNAME VARCHAR2(30);
BEGIN
  

SELECT USER_NAME INTO UNAME FROM FND_SIGNON_AUDIT_VIEW;
  

INSERT INTO APPS.neo_emp_verification_add (
      ADDRESS_LINE1,
      ADDRESS_LINE2,
      town_or_city,
      region_2,
      postal_code,
      person_id,
      date_changed,
      UNAME
      )
   VALUES (