If you want to add a filter to a layer in Photoshop, there are a few ways to do it. You can use the Filter menu, or you can use the eyedropper tool. The Filter menu has three options: blur, sharpen, and noise. The blur option is the simplest way to add a filter to a layer. Just click on the filter and then drag it around the image. The sharpen option is more powerful but can be time-consuming. You need to make sure that you have enough contrast before using this option. The noise option is more powerful but can also be time-consuming. You need to make sure that you have enough data in your image before using this option.