Go to the stock quote page, tap Options button, this will take you to the option-chain page. On this page it will display all related options including all expiration dates and strike prices.
Tap any option you want to trade and a page with a Buy and Sell button will appear. Select the choice you want to get to the details page.
Input all required order parameters, tap Review order to proceed. If order information is correct, tap Confirm & submit, the option order will be submitted to upstream broker.
If you want to modify or cancel an order, go to Portfolio page, tap Orders, and click on the order you just placed.
Tap Edit limit order to modify and re-submit if you want to change any parameters of the order, or you can tap Cancel order to directly cancel it.
If you want to trade multi-leg option strategies, like a straddle, just tap the dropdown list on the option chain page, select the strategy you want to trade, and tap OK to move on. The option chain will be updated to the strategy you selected.
Select any of the strategies, the bottom sheet will display the combo details with a Trade button. Tap the button to go to the order placement page. Input all required order parameters, when completed, select Review order, and finally Confirm and submit, the multi-leg order will be submitted to upstream broker.