CREATE TABLE t
(user_name VARCHAR2(20),
 pass_word VARCHAR2(15),
 cr_date DATE);  --User creation date

Insert INTO t
VALUES ('TEST', 'TEST', sysdate);

DECLARE
	v_userexist VARCHAR2(15);
BEGIN
	SELECT COUNT(*)
	INTO v_userexist
	FROM t
	WHERE user_name = :CONTROL.user_name;
	IF v_userexist > 0 THEN
			NULL;
	ELSE
        --Show your Alert here.
		RAISE Form_Trigger_Failure;
	END IF;
END;

DECLARE
	v_username VARCHAR2(15);
	v_password VARCHAR2(15);
BEGIN
	SELECT user_name, pass_word
	INTO v_username, v_password
	FROM t
	WHERE user_name = :CONTROL.user_name;
	IF :CONTROL.pass_word = v_password THEN
          :Your_From_field := :CONTROL.USER_NAME;  --This field is the filed in your attached picture
	ELSE
          --Show your Alert here that password is wrong
     		Raise Form_Trigger_failure;
	END IF;
END;

select manu_product_id,manu_product_desc,manu_lang into prodid,proddesc,lang
  from manu_product where manu_product_name=:manu_order.manu_product_name;