To short any commodity, you need to have something in hand, that is to say, you must hold a certain spot position to short. The specific operation procedure is: buy a spot in the futures market, then short the commodity, and then sell the spot after the spot price drops sharply to earn the falling price difference.

At present, you don't need to hold spot positions to short futures, but you can borrow spot from futures traders to short futures.

Reminder: the risk of futures operation is very huge. If you are short and the market price rises instead, you will lose money and jump off the building. For ordinary speculators, futures are not that interesting.