For adding Light rays to your image, make sure you first have an image that will properly support light coming through. You want to have an image that is either lit from the back or from the side. If all of the lighting is on the same side of the subject as the camera, a lighting effects will not work.
In this case we do have a lot of Light coming in above the model, so it will work to add Light rays. First we have to accent the light a bit more and make the light area even lighter. To do this we use Channels to select the Highlights and make that selection brighter with Curves.
To add the rays we use another Curves layer and bring up the Brightness. Then you can paint in Light and dark Patches wherever you want the rays to show up. The key in this process is to use a Radial Blur on ZOOM to make the paint splotches look like rays!
Adding Light Flare
You can use Photoshop’s built in Render > Lens Flare command to add a Lens Flare, in this video we show you a great alternative way to do it. We also show you how to add little light artifacts that make it really look as though light is hitting the lens.