How to put on the black ointment

Bake it ah, wait for it to melt and stick it on the affected area.

You can bake it on top of a non-smoking charcoal fire, fully burned honeycomb coal, alcohol lamp, electric stove

In fact, if there is a hairdryer blowing for a while longer, you can also let the plaster melt.

There is a layer of paper on top, which can be removed, and the paper or cloth at the bottom should be kept, or else or get the ointment on the clothes.