Summarize this article in one sentence.
Depending on what your shoes are made out of, you will need to either dampen them or heat them up. This method will work for most materials, including synthetics. Keep in mind, however, that leather stretches more than synthetic materials, such as vinyl and fabric.  Dampen leather or fabric shoes. Warm water is the easiest, but can stain or discolor the leather. A leather stretching solution would be safer, if you can find it. Heat shoes made from vinyl or urethane with a hairdryer. Keep in mind that this can damage some vinyl or urethane surfaces. Don't worry if the stretcher appears too small. You want it to fit loosely inside the shoe. If you have bunions, consider popping in the bunion attachment into the shoe stretcher first. Keep turning until you see pressure on the surface of the shoe. Don't overstretch your shoe; three or four turns will do. You can always repeat the process again if the shoes are still too snug. While the shoes dry/cool down, they will keep that stretched shape. Turn the knobs counter-clockwise until the shoe stretcher returns to its original size. Pull the shoe stretcher out. If the shoe is still too snug, repeat the process again. Keep in mind that some materials, especially synthetics, may return to their original size over time. If that happens, simply re-stretch your shoes.

Summary:
Prepare the shoes for stretching. Slip a shoe stretcher inside the shoe. Twist the knobs clockwise until the shoe stretcher fits snugly inside the shoe. Leave the stretcher on overnight. Loosen the stretcher and pull it out the next morning. Try the shoe on to see if it fits.