Just make sure the layer with your photo is selected, then go to Filter > Camera Raw Filter. Then click on the "fx" tool. You'll see a Grain section with a few different options. Play around with these sliders until you get the look you want!Aug 19, 2018
What apps add grain to photos?
Mextures. Mextures is a great easy to use app to apply textures, light leaks, grit and grain, and radiance. The app includes some great basic editing tools as well and has an ability to layer texture effects on top of other effects.