Shorting is what do you think when an asset is going down.
You can only short margined tokens or on futures. You can’t short spot tokens.
Shorting (short selling) is basically you buying a token for 10 and selling it to directly to your broker for 10. When price is lower, you will close your short/take profits. What actually happens is you buying tokens cheaper from market for 5 dollar each, so you can pay the broker back the token for a profit of the difference (5 dollar per token).
U should know about shorting:
Profits in shorts are limited, down is always max 100%, while up in (especially in crypto) can be 1000%.
Furthermore shorting is just like regular trading, manage risk etc because you are trading with leverage.
Binance has some good academy pages on how to actually use futures (buying and (short)-selling)
I advice to use FTX for crypto futures trading.