Place the skillet on the stove burner and heat it over medium-high heat. You need to use a dry heat, since the fat and oils in the walnuts will be enough to toast them. As such, you should not use non-stick cooking spray, oil, or butter in the pan. The shelled walnuts will toast best if divided into halves or quarters, but since it is easier to monitor the toasting process on the stovetop, you can also use smaller pieces if desired. Try to keep the walnuts on a single layer to promote even toasting. Stirring the walnuts allows each one to be exposed to the heat for an equal amount of time and, as a result, you will get more evenly toasted walnuts and find fewer burnt nuts. Stirring constantly is best, but you can allow the nuts to rest for brief periods as long as you still have an eye on them. The process should only take about 5 minutes, but may go even faster if you have small pieces. Once done, the walnuts will be a deeper shade of brown and will smell toasted. Immediately transfer the nuts out of the pan once done. Otherwise, they will continue to cook on the hot metal. Transfer them to a heat-resistant bowl or dish and let them cool until they reach your desired serving temperature.

TL;DR in Chinese:
加热一个大锅。 将核桃倒进锅里。 经常搅拌。 烤到变成褐色。 从火上移开。