i can lock the car with the key the central locking work that way and but the fob will not work and i have change the battery in the fob and the red light comes on but will not lock the doors
Turn ignition on (dash lights on, don't start engine), press lock button on key fob, doors should lock then unlock, job done. If it doesn't work first time give it a couple of tries.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix cars.