Head down to the Tone Curve to make a fine adjustment to contrast. Use one of the presets from the pulldown, adjust the curve directly, or use the slider to add a bit more contrast to the scene. Then zoom in to adjust the grain. You can individually choose the amount to add to the shadows, midtones, and highlights. And, best of all, you can tailor the grain size to your simulated film. If you plan to crop to a 4x5 ratio, or if you just prefer smaller grain, call your image large format and set the grain size accordingly (it will appear smaller the larger the film size you choose).