I usually put the texture(s) under all my images, like a background. You know the Hayden banner I made you? The green on the right is a texture, and I have the image and brushes over it. the other way I do it sometimes is like in this wallpaper:
I have a texture on the bottom, then I have the same one on top of everything at 25% opacity, or somewhere around there.
I'm sure there are other ways to do it too, but that's the way I do it
