Layering 2 Images

Firstly, I chose the 2 photo's I wanted to use, from my folder, and had them as 2 seperate tabs.

I made sure Auto-Select and Show Transform Controls were ticked so this means I could rezise the photo I'm using to layer with the other photo.  

I then dragged the photo over the other photo, so it was covering it completely, and then I resized the top layer so that it was the same size as the bottom layer.

This is how it looked when I resized the top layer.

Afterwards, I clicked on the arrow next to Normal, and changed it to Multiply. 

Then I changed the opacity to 50% so that you could see both photos together in one.

This is the final photo after layering both images together.