How to place a market order?

A Market order is designed to be executed immediately. It is meant to buy or sell at the best available price in the order book (which you can view before placing an order). Note that this is different from the last traded price. 

To place a market order, you need to click the trading pair you want to trade and go into the trading page -

Choose market order, and put the amount you want to buy/sell. The price will be the best market price at the moment when the deal is done.

Keep in mind that you’re not guaranteed the exact price you’re trying to buy or sell at. It all depends on what is available in the order book when your order is being executed.