First of all, you need to open an account and trade all accounts in the name of a member of a futures company. Then use the funds under this account to buy and sell contracts on various varieties. To put it simply, you think cotton should go up. Let's buy this cotton contract. He goes up, you make money. You think she'll fall. You just bought a contract that she would lose. He really fell. You also made money. It's that simple. More specific and detailed related knowledge can be exchanged with me.