The simplest way to place an order to be executed at the current market rate is by left clicking on the exchange rate within the dealing rates window for the currency pair you wish to buy or sell.

After left clicking on the exchange rate for the currency pair, a "market order" box will appear.  In the market order box there are 5 parameters
which can be set prior to sending the order to the trading desk:

• Select the account you plan on trading on, though this is only applicable if you are trading in more than one account.
• Select a currency pair. This will default to the currency pair that is highlighted in the Dealing Rates Window, or select another currency from the drop down box
• Select sell or buy
• Select the amount you are buying or selling, trades are made in increments of 100,000 of the base currency. "100" represents 1 lot, or 100,000 units of the base currency. "200" is 2 lots, or 200,000 and so forth.
• Under At Market, select the range of rates you are willing to accept.  Orders will be executed at the first rate the market reaches that is within the range specified here. Most traders will want to leave this at “0” unless they fall in to the possibility of their order coming in at an off-market price.
• To activate the stop or limit feature, click the "Advanced" button on the box to the left of the word "Stop" or "Limit."   For more information on stop and limit orders see Stops and Limits.
• Click the "OK" button after all the selections have been made to execute the trade. After "OK" has been selected the trade will appear in the "Open Positions" window, which confirms the execution of the order.

Right-click on the appropriate rate and select the "Create a Market Order" command from the pop-up menu that appears.

Click on the "Buy" button at the top of the trading screen.

Click on the "Trading" heading located at the top of the screen and select "Dealing Rates" and then "Create a Market Order"