Adding Nav Bar Menu Categories

Hi. I just installed the Simple Catch Pro "over" the free Simple Catch theme. Everything turned out perfect and exactly as it looked in the Simple Catch--except the nav bar, which now only displays the pages. How do I get the nav bar to display the categories? All of the categories I had with the Simple Catch theme are still listed there and all the posts are still associated with the categories, but the categories are not showing up on the nav bar. Thanks in advance.