The Geometry Manager window will automatically link the Attach From object to the Selected Object. The Attach From object appears in the middle of the window with a radio button on each side. This symbolizes which side of the object you are going to attach from.
The Attach To object has two radio buttons, which symbolize which side you are going to attach to. These are location on the top and down when using a vertical attachment; and left and right when using a horizontal attachment.
The dropdown menus have the eligible objects that can be attached. A number specified in the offset field will determine the offset in pixels.