WAY NUMBER 1.
Take out your image. I got my image from ashley-t.

--OPTIONAL-- You can cut the image in WHOLE, or you can cut it in pieces. I recommend cutting it in pieces.

1) Cut it using the FREE HAND SELECTION TOOL. It looks like this:

2) Match my settings:
3) Now, cut the outline of the picture like this:

4) Once you're done cutting it, it should look like this (or better):

Save it as a PSD.

WAY NUMBER 2.
1) Open up a transparent backround, and paste your 2+ pictures on there. Make sure they overlap, like this:

2) Go to your tool bar, and open up ERASER TOOL (X).

3)Now, click on that, and keep that settings the way it is. If you want, you can make the eraser bigger. Erase on where it overlaps, like this:

4) After your done, the picture should look like this (or better lol):