Another easy task!

In this task you are placing an image partially over another one.

Example:

The final image:

In the final image the inserted image is not dominating the original image. That's important!

1/. Find two images that will work for you. The background image should not show the faces too clearly, as the effect would be lost.

2/. Resize the top image to a workably proportioned size.

3/. Copy/Paste the top image over the background image.

4/. Using the Free Transform Tool adjust the top image to size in. That's Edit/Transform/Free Transform, then using the handles resize your image.

5/. Add a Layer Mask to the top image. Layers/Layer Mask/Reveal All.

6/. Select the Colour Gradient Tool. (If not shown, it will be under the paint bucket).

7/. Select a suitable colour for your gradient, from the colour swatches, then drag the mouse from the top right corner down to the bottom left. If the colour is not dark enough you may need several goes at this. But you do not want it too light or too dark!