If it's the correct touch up paint from your Alfa dealer, then it should come in a thin tube, which you apply with a brush. Shake it to agitate the metallic particles. This also has the effect of making the color slightly less dark after your apply it. If the paintchip is very small, it might be better to file down a toothpick and apply it with this. Always remember to use the minimum amount possible. Let it dry for an hour or so. Just apply another layer if you think it needs more. And remember to apply the laquer when you are done.