Well, the contentPane of the the JFrams already has a layout. It simply needs to be used correctly. If you use add without any anchor parameter then according to the documentation As a convenience, BorderLayout interprets the absence of a string specification the same as the constant CENTER
So, simply calling add(Component) twice, is the same as calling add(Component, CENTER) twice. She should be calling add(Component, CENTER) and add(Component, SOUTH), for example.
Of course, changing the layout (as your post showed) is always an option, but is not, strictly speaking, needed.