help query

hi everyone,

i've got this oracle query, and i need it to put it to work in potgresql 
platform, i think the right outer join it will do just fine, but i don't 
now where to put , can anyone help me:

select id_mensagem, ds_description, e_mail,
to_char(date,'DD/MM/YY - HH24:MI') as Date, assunto, respondidas,
mensagem, mensagens.id_respostafrom (select id_mensagem, ds_description, e_mail, date, assunto, 
mensagem, id_respostafrom tb_mensagens_monitoreswhere tb_mensagens_monitores.id_resposta is null) mensagens,(select
id_resposta,count(id_mensagem) as respondidasfrom tb_mensagens_monitores group by id_resposta) as respostaswhere
mensagens.id_mensagem= respostas.id_resposta(+)
 
order by date

kind regards,

rute