You can arrange your pages in hierarchies by selecting a top level page for your other pages. For example, like this:
Click on the navigation menu at the top of the screen to open its settings.
There are 2 ways to create sub-pages:
1. On the left menu, drag a page underneath and to the right of another page.
2. Choose the item you want to nest and specify the top level page.
Publish your website to apply the changes.