It quite a fidley thing to adjust, and also you'll also end up scraping some of the paint of the bolts within the process.
You need a Clamp Wrench/spanner and a spanner.
You basically need to loosen the thread to make the damper longer to provide that tightening effect.
I remembered using a spanner on the blue damper tube end where it has the cut out grooves for the spanner to fit. Try twisting this first counter clockwise. Then I think you also have to clamp onto the round grooved nut and twist that as well.
Sorry, I cant remember how I did it and I'm out of town atm, so cant check my car... but try that out. Hopefully you'll work it out during the process. Be warned though... you might end up scraping a bit of the paint off the orange bolts. which is necessary.