Create a dividing line and place it between two widgets.
To make a widget visible on the website you must add it to a page or to a layout. On the page about widgets you can read how widgets are placed within the page or layout.
After releasing the widget dividing line to the correct location, the settings screen will be opened.
Management Centre > Site Management 2 > Manage dividers
Here you can design the dividers that you can use on your website.

