STEP 2: OPEN A PHOTO THAT WITH ROCK TEXTURES
I am going to use below shown photo. It has pretty nice patterns which is best for grungy look.
Now press ctrl+A/cmd+A to select all the image then press ctrl+C/cmd+C to copy the image. I am going to paste this image in my original document. So go back to your original document and press ctrl+V/cmd+V to paste that.
Select move tool from the left panel or press V. Make sure that the show transformation controls is turned on in the top panel. Now adjust the image the rock pattern such that it totally fits on your photo.
