The map image is made up of translucent dot patterns that takes the shape of a global map. I'm saying this so that you can understand first what it is made of.
Now if you want to replicate this pattern on to another image, you will first need to great the dot pattern. It's not easy to explain here how to do this as we will need to do screen shots and videos to show you. I figured that you don't really know how to use Photoshop. You can Google "Photoshop patterns" to learn how to create them.
The only other think other than creating the pattern is to drop the opacity of the layer to your liking and then save it as a 24-bit PNG file.