1. How to use margin?
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.
2. How to sell short?
On the trading page, you can see the number of "available to sell short". Only when you have no long position of the stock, you can place an order to sell short.
When you don't have a position in a stock, entering an amount larger than 0 and selling will generate a short sell order. The order confirmation page will remind you that the current order is a sell-to-open order, and will also show you the current short rate in the order details (please note that the short rate is only a reference value in the intraday market, the actual rate is subject to the rate of daily settlement time, please pay attention to the daily statement).
When you sell short a stock, select the current stock again, the page will show the number of stocks you hold (Hint: to close the position you need to buy back). In your position page, the number of your short positions will be shown as a negative number.