Before attaching the reed to the mouthpiece, you will need to moisten it in order to make a good sound. A dry reed is not flexible enough to make a consistent tone and may be totally unplayable. Some players like to place the reed in a glass of water before using it, while others prefer to use saliva by putting the thin end of the reed gently in their mouth for a short period.
Once the reed has been moistened, slide the flat part of the reed along the flat part of the mouthpiece until only the very tip of the mouthpiece is visible behind the reed. Once you are happy with the position of the reed, hold it with your thumb while you slide the ligature loosely into place and then tighten the screws, but not too tight. The ligature holds the reed in place so that it doesn’t move when you are playing. To avoid damaging the reed, try not to touch the tip of the reed as you adjust it’s position. If the reed is damaged, you will find it difficult or impossible to produce a good sound.