Putting Objects Behind One Another
Place your object where you want it in the scene
Notice what objects in the scene need to move in front of your placed object
Zoom in on the object
layer in the Layers palette
Turn off the inserted object layer
Very CAREFULLY select the object that will move in front - if the object is large this can be done in pieces -
Set feather at 0
Set anti-alised ON
Click CMD-J to copy and paste your selection onto a new layer
When you have all the pieces of the selected objects on new layers:
Make ONLY those layers visible (turn off the Background Copy too)
to merge the layers
Name and move the single new layer to the inserted objects's set and make sure that it is above the object so that it will display over it.
!!! Remember: Attention to Details !!!!