To use the backgrounds, simply import the background into your 3D program.
Creating an alpha channel in Photoshop: Render the scene in Poser on a black or white background. For larger images, you may have to render to a larger window. In render options, you will find the dimensions for the new window. Put in the same dimensions of the background you plan to use. Then save or export the image as a tiff. In Photoshop, open the tiff you just saved and click on the Channel window, behind layers. Hold down cntrl and click on “Alpha” It will outline just the render contents. Then go to Modify and contract the size of the outline by 1 pixel, or you may end up with jagged edges. Lastly, go to edit and hit copy and then paste it into your background and it will paste the objects in the scene as a new layer.