Creating Sub-Navigation pages is great if you are looking to have more pages in your Navigation Bar, and want them in a drop-down menu.
1. Select Content in the gray navigation bar and locate the Pages you would like to change.
2. Use the Arrow icon on each Page block to nest the pages under the main block, which will be seen in your navigation bar. Using the arrows will nest it directly below the page it is following, thus making it appear as a drop-down menu under that navigation link.
Note: Move the order of your pages by using the grabber icon (the three lines on the left side of the blocks).