A face in the leaves. With two examples - it's easy!

The finished image examples. You only need to do one of these, or you can do two different ones!

1/. Find two images. One of a person and the other a background to work with. The background image should be larger than 2MP. The "over the top" image should be proportionate to the background size.

2/. Open the Background Layer. Using the Layers Window, select the Layer Mask. In the dialogue window reduce the Density to around 40%.

3/. Then reduce the Opacity in the Layers Window to around 45%. (The exact amount for both depends on the image you select and it's brightness and contrast.
4/. Open the "over the top" image and remove the background - Image Size, File New the same size and transparent.
5/. Copy/Paste the original image to the new image and remove the background, first with the Magic Wand Tool, then the Eraser for any tidying up.
6/. Save this image as a Compuserve G.I.F.
7/. Copy/Paste the image over the background image and position it with the Move Tool. (Top of the Toolbar).
8/. Then reduce the Opacity on the top image to about 40%, to fade out the image, so it is just seen.

9/. Save the finished image as a .JPG.

Here's the two examples finished.