I did mine before, piece of piss. Jack the rear of the car up and release the handbrake so the wheels can spin freely. Pull the driver's seat all the way back, and pull back the rubber cover over the bottom of the handbrake handle. You'll see a threaded rod with a 10mm nut on the base of it. Turn the nut clockwise to tighten, check the tightness, and adjust accordingly. Make sure the wheels still spin freely with the handbrake down though, you don't want to over-tighten it.