Jack up, put it in gear,
make sure it wont move, undo your handbrake..
Take off the heatshield above the centre exhaust section (10mm bolts - probably rusty and snap off

), the adjuster bolt is there. You will need a 13mm (or 14?) deep socket. Tighten it a bit at a time then check the handbrake - it should get fairly tight on about 4 clicks but the wheels should obviously move freely when its off.
If you want the heatshield back on then you will no doubt have to drill the snapped bolts and use new ones.