If you've got height adjustable suspension you can raise or lower the car at your will to suite the circumstances.

With your adjustable suspension you should have recieved 2 'keys' which are required to make the adjustments.

At the base of the coil spring you will see to 2 lock ring nuts.

Attach the keys into the notches on the lock rings. You want to be effectively loosening the lower ring, but moving them both together will make this task easier!

Spin the lower ring down (just so it's out of the way).

Since the suspension strut is held firmly in place by the clamping plates at the base of the shock, you can simply grip onto the spring itself and twist to adjust. This should move the lower lock ring up or down the thread accordingly, raising or lowering the suspension as desired.

Once you're happy with the height, spin the lower ring back up, and tighten with the keys.

Remember to ensure you count the number of turns on each corner of the car to ensure they're even.