Add textures

There are several options in the Blending Modes menu for adding texture. Explore Overlay, Hard Light, and Soft Light, which give precedence to the lightest and darkest pixels in the blending layer, leaving most of the middle values translucent. Try dragging a photo with a texture into your file, place it over the layer you want to add texture to, and switch the Blending Mode to Overlay. You can then erase away at the layer to leave texture only where you want it.