Quote - Again here is the steps for using the free UV mapper program

Step 1. create a box from props (Poser 8)

Step 2. load it into UV mapper (free)

Step 3. File - Save texture map (it will create a .bmp file in the geometries folder)

Step 4. File - Save model (it will create an .obj file in the geometries folder)

Step 5. File - Export  (it will create a .uvs file in the geometries folder)
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Step 6.  Import your .obj file box from the geometries folder

Step 7: Go to the materials room and connect Diffuse Color - New Node - 2D textures- image map  - yourpic.jpg from yourTextures folder

Actually, I would like to add this forumula doesn't always work.  If you want a 2 D image on one side of the box (another example would be a picture on the front of a T-shirt) then you have to use a one sided primitive.  In Poser 8 you could try the thin one sided sheet under "Primitives".  However, if you just want to add color then you could map a colored .jpg to a 3d box but simply changing the color on "diffuse color" is easier.