how did COVID-19 start in exact detail?

There was a market in Wuhan China that sold exotic foods and the one that carried the virus was a species of small bats who are immune to the virus so they are carriers. The conditions at these open air markets are very unsanitary and the virus was able to jump form bats to infect humans. Since it was slow in showing symptoms it quickly spread and even when a doctor discovered it the Chinese Government disavowed his claim and eventually he died form the virus. Since they were slow in reacting people traveled from Wuhan all over China and all over the world before ti was realized that the virus was spreading so it was turning up all over the world before proper steps began to be taken to attempt to control it.

It was created in a Chinese laboratory and is being used as a bioweapon.

As has been said except for the alt-right minion. Detail? We will never know which vendor had which animal that had the first ever virus. But the market in Wuhan is known to be the epicenter.

The latest thinking is that it was spread via wildlife killed for food, China put a total ban on all wildlife being sold as food in the food markets last week. Canines are known to be susceptible to variants of the corona virus, there was a potential that foxes were the initial vector with the new mutation.

I don't think we know yet.  It probably started in an animal.  Many new diseases which emerge in humans began in another species and then jumped the species barrier to humans. 

We don't really know. They have traced it to a specific open air market in Wuhan China, the specifics from there are unknown. 

It didn't start in detail. I read it started in dehead.