You can even do it without tools, just grasp your glasses by the bridge between thumb and forefinger, but do not hold by the frame or lenses! Then gently push the nose pads together. Try not to do this too often, or you will wear down the metal.
Before repairing, you should check weather the sides of the nose pads are not close enough to your nose, if yes, you can just fix them with your hands. However, if the screws of nose pad are loose, then a special screwdriver is needed to tighten them. I suggest you do not use the tools at will to avoid damaging the glasses frame.