This is a short video on how to create a dropdown menu button on your site. To get to this page on your account go to Settings > Menu.
The first step in this video is creating the Parent, or Top Level, button. This will be the button shown on the menu bar that the other buttons fall under. It is important to not use a button that is linked to a page on your site. Parent buttons can't be used to link to another page.
Next you will drag the desired links under the newly created Parent button with the arrow key icon.
Then you can reorder the menu buttons however you like.