Please, does anyone know where I can find dental floss?

You can definitely find it at Carrefour, next to all the toothbrushes. You can probably find some at other supermarkets etc. as well, although I've never really looked. If all else fails, try asking at a dentist, they might be able to sell you some.

Watsons drug stores.
Their own brand flossers (on stick) are good.

Don't buy the stuff at Carrefour, it's poor quality and shreds easily.

Try Watson's I got some OralB floss from there last time.