I'll just paste what I told you in the PM I sent you when you asked me for some tips.
There are several ways to do it. One way is to switch the blending mode on the layers palette until you see something you like. Or you can just fade it with the Opacity or Fade options on the layers palette, but alot of times that's not enough. Another way that has become popular not too long ago is to duplicate the picture you want to blend, set the blending mode to lighten or screen, and motion blur it(Filter, Blur, Motion Blur). And if it's too bright or something, and you want to fine tune the look, you can change the brightness/contrast(Image, Adjustments, Brightness/Contrast). Another trick that you can do with a pic is duplicate it, set the blending mode to lighten or screen, and gaussian blur it(Filter, Blur, Gaussian Blur) and do it at maybe 2 or 3 just to soften it and blur it a bit. Then you can fiddle with the contrast and brightness for a final touch. That's all I can think of right now.