I'm going to assume that is not the resolution of your monitor and you are in window mode. If so, move the mouse over any side of the screen until it turns into a double headed arrow and then press and hold the left mouse button while dragging to make the screen any size you want. Or check the box for full screen in the launcher settings. I've not noticed any performance hit for running in window mode and it allows you to have content manager open while in the main program running trains.
William