A sub menu is a way to prevent your design from getting cluttered with link while still providing navigation to all the pages of your website. To create a sub menu follow these steps.
Step 1: From the editor view click on the pages icon on the left side panel. This will take you to the page management area.
Step 2: Drag the main page you’d like to covert into a sub page by dragging it underneath your desired parent page.
Step 3: Drag the child page to the right so it appears indented underneath the parent page. A small arrow will appear on your navigation menu indicating if you click on the parent page you’ll be able to navigate to child pages.