The OrderToBack method moves a shape to the front of the stacking order.
Examples:
The following VBA example creates a page frame rectangle and places it behind all other shapes on the current layer.
Sub Test()
Dim Frame As Shape
Set Frame = ActiveLayer.CreateRectangle(0, 0, ActivePage.SizeWidth, ActivePage.SizeHeight)
Frame.Fill.ApplyFountainFill CreateRGBColor(255, 0, 0), CreateRGBColor(0, 0, 0)
Frame.OrderToBack
Frame.Locked = True
End Sub