Using sky backs as a light souce
Remember when resizing things for use to apply a sharpen to keep it looking crisp. I needed the background to have a misty, mystical feel to it so you do the same for yours. Save often.
Layer 1. Background -- normal
Layer 2. Duplicate layer, set to 31% opacity and choose subtract.
Layer 3. Sky of choice -- overlay 100%
Layer 4. Duplicate sky layer and set to 32% choose Hue
Layer 5. For the light rays:
Choose brush and use 24-32 point soft brush
Make dots in the places you want the lights to show, not all over but like where the ends will touch the image
Choose motion blur with a radius of 14 or the angel of the lighting of original image
Make duplicate layers of each light layer and choose overlay or soft
Add your main images where you need them to be BUT put their layer at the bottom of the layers of lighting.
Save.