1. Log in to your Blogger Dashboard.
2. Go to Design -> Page Elements -> Top Menu –> Edit


3. To create submenu items simply add in front of submenu title (name):

"-" for 1 level submenu (without quotes)


"--" for 2 level submenu (without quotes)


"---" for 3 level submenu (without quotes)


- represent dash
NOTE: The Submenu item should be placed below the parent menu item. For a menu like in the images the setup should look like this: