How to add film grain to your images in Photoshop Elements using filters
Start off by duplicating your ‘Background Layer’ by going to Layer>Duplicate Layer, and naming this ‘Film Grain’.
Head to the Filter menu and then down to Filter>Texture>Grain. Change Grain Type to Stippled and set Intensity to 44 and Contrast to 52.
Use the Preview option in the filter to assess the grain effect, but your image should now be monochrome. Hit OK to apply these settings.
In the Layers palette lower the Opacity of the duplicate layer to 50%. The strength of the effect should look less imposing and more colour will show through.