The Layout | Arrange | Send to Back command moves the selected object or objects to the back of the plot document. The object will appear behind the other objects. Alternatively, right-click the object and select Order Objects | Move to Back.
Objects can also be moved by dragging them to a new position in the Contents window.
The default keyboard shortcut for the Layout | Arrange | Send to Back command is SHIFT + PAGE DOWN. The keyboard shortcuts can be customized with the Customize command.
In the left drawing, the red square is located in front of all the other objects. Use Send to Back to move the square to the back layer so that it appears behind all of the other objects (right drawing). Send Backward moves the square backward one layer at a time.
Bring to Front