i have one question, why you dont search in gogle for more information about your issue? I tried with the following query "sintaxis join informix" and i received many links and this is one example:
http://aam.ugpl.de/?q=en/sql_help/inner_join
If you read the link, you can discover that the JOIN in informix doesnt exists, instead of JOIN you can use INNER JOIN or the classic
select * from table1, table2 where table1.id=table2.id
please try searching information in google, and later if you have more questions come at this forum :)
regards,
Libras