Request over partition and join

Hello,

I'm trying to get a report using partition and joins.

The involved tables are:

ligne_ordres with
- non unique composite key titre_id, date_ord, numero_ordre,  
operation_id
- foreign key titre_id to table titres
- foreign key operation_id to table operations

titres with
- field societe

operations with
- field libelle

I need to get the following report:

id   societe   date_ord   numero_ordre   libelle  ppb  pf   ppn  tpb   
tf  tpn

With the following code I get:

id   titre_id  date_ord   numero_ordre   operation_id  ppb  pf  ppn  
tf  tpn

How to integrate societe and libelle into the report instead of  
titre_id and operation_id?

[code]
WITH calculate_parts AS (
	SELECT id, titre_id, date_ord, numero_ordre, operation_id,
	      CASE
	        WHEN operation_id != 2 and operation_id != 21 and  
operation_id != 23 THEN
	          prix_brut
	        ELSE
	          -round(quantite * cumpb - 0.005, 2)
	       END AS prix_brut,
	       CASE
	         WHEN operation_id != 2 and operation_id != 21 and  
operation_id != 23 THEN
	           frais
	         ELSE
	           -round(quantite * cump, 2) + round(quantite * cumpb, 2)
	       END AS frais,
	       CASE
	         WHEN operation_id != 2 and operation_id != 21 and  
operation_id != 23 THEN
	         prix_net
	       ELSE
	         -round(quantite * cump, 2)
	       END AS prix_net
	FROM ligne_ordres
	WHERE date_ord >= '2011-03-01')
SELECT DISTINCT ON(titre_id, date_ord, numero_ordre, operation_id)
   id, titre_id, date_ord, numero_ordre, operation_id,
   SUM(prix_brut) OVER (PARTITION BY titre_id, date_ord, numero_ordre,  
operation_id) AS ppb,
   SUM(frais) OVER (PARTITION BY titre_id, date_ord, numero_ordre,  
operation_id) AS pf,
   SUM(prix_net) OVER (PARTITION BY titre_id, date_ord, numero_ordre,  
operation_id) AS ppn,
   SUM(prix_brut) OVER () AS tpb,
   SUM(frais) OVER () AS tf,
   SUM(prix_net) OVER () as tpn
FROM calculate_parts
ORDER BY titre_id, date_ord, numero_ordre, operation_id, id
[/code]

Thanks in advance for any help.

Cheers,
Michèle