Adding photos to games

[CelerEtAudax]

I have been trying – unsuccessfully – to add a photo to one of the East Front scenarios I have made.  The first thing I did was to boot up Photoshop and I opened the Klepchevo photo used in one of the stock scenarios to use as a model.  I then loaded the photo I was intending to use.  Using the ‘image size’ box, I changed the pixel dimensions and document size to match those of the model.  I altered the format to bmp and changed the name to match the file name of my scenario.  I then saved the modified photograph,  fired up the game and scrolled down to the scenario.  However, there was only a black rectangle where the photo should have been.
I have checked and re-checked the manual, but there doesn’t seem to be anything in it that shows you how to add photos.

Can anybody help?   

Richard