create data base link in oracle

CREATE PUBLIC DATABASE LINK name_of_link
CONNECT TO oracle_username
IDENTIFIED BY password -- double quotes here
USING 'database_sid' -- single quotes here ;

eg.
CREATE PUBLIC DATABASE LINK talkies
CONNECT TO username talkies identified BY "talkies123"
USING 'vxmldb1';

/
-- test the dblink
select * from dual@name_of_link
/