If it is the Citroen Picasso after the 55 reg. there are two bolts, one in each of the seat runners, there is a tool under the nearside rear floor which looks like an allen key, this is what you will need to use to remove the bolts unless you have some torque keys to fit them. Once these bolts are removed the seat will fold forward but you will need to ensure the seat is pulled fully back once the bolts are removed. If the car is prior to a 55 reg. then the seat can be tilted by using the two levers which R1Geezer has told you about, and you lift the cover from the battery but remember to put it back afterwards as it will prevent the live terminal shorting out if it comes into contact with any metal surface should anything fall underneath the seat. Hope this helps