First get the two pictures you want to blend.

Now set it how you like. Then click "Add Vector Mask" located here.

Now make sure you foreground color is set to black. Now select an
interesting brush and start blending.


Changing the opacity or changing the color from black to a shade of
gray will effect the amount of the picture blended.
If you mess up dont worry. Just switch to the color white. And repaint
the areas the you messed up and you picture will reappear.
Now just add you own touches and a border and your done. Hope this was
helpful.
This is what I came up with.

And remember if you like this tut please join up and hang out.