You have to remove the bezel around the handbrake, then lift the rubber boot, you will see where the cable wraps around the lever mechanism, On the end of the cable you will see a 6 or 8mm nut, A 10mm spanner or long socket will fit. Just take up the slack, but don't over do it as the handbrake will stay on.. I have circled where the adjustment nut is. You may need to check the cables and handbrake pads in the rear calipers.