You can add a legend to your contour which shows the levels of the contour in their increments. To add a legend, select Insert ® New Legend from the iContour tool window.
Once you have placed a legend on your contour can edit the legend settings such as the title and level increments as well as the color options on the legend. Double-clicking on the legend itself will show you the Visualization Browser. For more information on the options available, see Legend Properties, "Visualization Properties".