To use the die to create new threads on a worn out bolt, place the bolt into a vise to hold it as the wrench is turned over it. Cutting metal with metal can create heat, so put some cutting oil on the bolt to lubricate it. Place the die over the bolt and hold it horizontally. Turn the wrench. The die will catch on the threads already cut into the bolt. Every couple of turns, reverse the wrench about a half a turn to clear the threads so that the die will cut better. Also, re-apply cutting oil throughout the process. Turn the wrench until the bolt comes past the top of the die.