Right-click anywhere in the 'Chart' window for the instrument you wish to place an alert on. Hover the mouse over the 'Trading' button, and then select 'Alert' in the menu that opens to the right. Once you've clicked on it, go to the 'Terminal' window at the bottom of the platform, and click on the 'Alerts' tab. Find the alert you just entered and double click on it. In the window that opens, you can alter the alert conditions to your requirements.