Hello Sajan,
There are many shops, one of the bigger in France is called "Conforama" (and reasonably priced). You can have a look at their products and prices online at
http://www.conforama.fr to get an idea.
You have Ikea also (
http://www.ikea.com/fr/fr/) their prices are higher, but you may find that their quality is sometimes better.
These sites are in French.
It really depends also what you want in terms of bed and bedding related items.
Designed bed furniture (those may be sold without bed base and mattress, which you then have to buy in addition):
http://www.conforama.fr/rayon3_chambre-et-literie_chambre-adulte_lit-adulte_10001_10602_-2_148080_148083_148081
Mattresses:
http://www.conforama.fr/rayon3_chambre-et-literie_literie_matelas-2-personnes_10001_10602_-2_148080_148101_148099
http://www.conforama.fr/rayon3_chambre-et-literie_literie_matelas-grande-largeur_10001_10602_-2_148080_148102_148099
Or for the first weeks of your stay, a plain combo bed-base and mattress may suffice:
http://www.conforama.fr/rayon3_chambre-et-literie_literie_ensemble-matelas---sommier_10001_10602_-2_148080_148105_148099
These are big stores. For Conforama, you have 3 in Paris, the most centrally located one being Conforama PARIS PONT-NEUF, in the 1st district in Paris. This address has links to Google maps locating their stores:
http://www.conforama.fr/magasin-conforama_ile-de-france_10001_10602_-2_1_12
If your apartment is in the suburban area, there are also many stores in the towns around Paris (see the link above).
They make deliveries and install the items for you. For beds, it is quite reasonably priced:
http://www.conforama.fr/service_livraison_10001_10602_-2_7
You will have to be there at the time the delivery happens.
Good luck, and welcome to the city of lights
