The bicycle brakes are now fixed and I also put some oil (rapeseed oil) on the pedals to take out the creaking sound. The rear brake was easy to adjust, I simply turned a knob at the back of the saddle. The front brake was also quite easy to fix, but I had to use a wrench. The screw-nut was partly worn but the brake got better. I also oiled in the gear levers a little bit, the pivot point on the brake levers at the handle bar, the chain and the front- and rear- derailleurs.