If the order amount exceeds the cash purchasing power, the system will automatically use margin to purchase; if the order amount does not exceed the cash purchasing power, it will only use the cash to purchase.
On the trading page, you can see the number of "available to sell short". Only when you have no long positions of the stock, you can place an order to sell short.
When you don't have a position of the stock, entering an order quantity and selling it will generate a short sell order. The order confirmation interface will remind you that the current order is a sell-to-open order, and will also show you the current short sell reference rate in the order details (please note that the short sell reference rate is only a reference value in the intraday market, the actual interest rate is subject to the daily settlement interest rate, please pay attention to view the daily statement).
When you sell short a stock, select the current stock again, the interface will show the number of stocks you hold (Hint: to close the position you need to buy back). In your position interface, the number of your short positions will be shown as a negative number.