SQL & PL/SQL

I have created this sequence

CREATE SEQUENCE COUNTRY_SEQ
START WITH 1
MAXVALUE 9999999
MINVALUE 0
NOCYCLE
NOCACHE
ORDER;


Now i want to generate alphanumeric sequnce no,

so for that i have create trigger.But in java trigger is not working directly.Now we think to work on function

I have created function also but i am confused how to use this function while I am inserting in table.

My function is
like

CREATE OR REPLACE FUNCTION ss_thresh
RETURN NUMBER AS
lSeq NUMBER(9,2);
BEGIN
select COUNTRY_SEQ.NEXTVAL into lSeq
from dual;

RETURN 'COUX'||TO_CHAR(lSeq, 'fm0999999') ;
END ss_thresh;

is it true.And i dont know how to integret this function with my table