Make sure to really saturate the wrinkle with the oil so the leather around it will become supple. The oil will help protect your shoe from damage when you apply heat to the leather. You can buy leather oil, such as mink oil or neatsfoot oil, at a specialty leather shop or wherever leather shoes are sold. Move the nozzle of the heat gun around, never staying in one place for more than 2-3 seconds. The whole process will probably take about a minute. Lighter leathers are susceptible to discoloration when they’re exposed to heat, so test a small area on the heel of the shoe before applying heat to more visible areas. The combination of oil and heat should make the leather pliable. Use your hands to stretch and smooth the crease until it starts to fade. Insert the shoe tree as tightly into the shoe as you can. As your shoe cools, the smooth texture will become permanent. Be sure not to tighten the shoe tree too much. Since the leather is hot, it will be prone to stretching.

How would you rephrase that briefly using Chinese?
用皮革专用油浸湿折痕。 用热风枪或吹风机软化鞋面的皮革。 搓揉皮革直到折痕消失。 冷却时，在鞋中放一个鞋撑。