[ChelseaFan]

Here's a more effective one, and easier .

Get the 2 images that you want to blend and put one on top of another like so



Now go to Layer>Add Layer Mask>Reveal All

Ok now take the gradient tool and have your foreground white and background black

put the gradient across your images like this



Go over it a few times until you have it perfect

.

This one is much better