Once you click on a particular prediction, you will see the deadline of that prediction and open orders if any. Each open order that is not yours will have a Take button, which allows you to quickly offer to FILL that order to create a contract. For example, if there is a BUY order for 2 contracts at 0.5 each, press the Take button means you will sell 2 contracts at 0.5 each. Below that information is an order form. You can fill in your order type (BUY or SELL), price, and quantity, and submit your order.
If your order is accepted it will list in the open order list with a cancel button. If your order matches against an existing order, it will be filled and shown in your
positions page (discuss later).
NOTE: Some predictions can be determined before the deadline. Your open order will still be available for match before administrator determines the outcome. You are responsible to cancel your open orders when outcome is known.