Can you explain how do the dentist do a root canal?

Open, Clean, Seal.: "root canal" is a hollow, tunnel-like space in the tooth's root(s). Rct, or root canal therapy, is to gain access to, clean out its nerves ; blood, disinfect, and fill. The tooth will be numbed first, then a tooth-cover called a rubber dam is placed to separate the tooth from oral germs. After rct, the top hole is filled. If the fill is temporary, you will need a final fill or crown soon after.

Like Any Wound: If you think of a tooth infection like an on-going wound, it's treated just like any other wound in the body: the area is numbed, the wound is opened & cleaned, some sort of disinfectant/medicine is placed, and then it's closed & kept clean so it can heal. The difference with a tooth is that it's a hard structure, not soft like skin or muscle, so it takes special steps to get inside to clean it.