I personally use Corel Photopaint, but I would think PS would work to. Either reduce your image to the largest demension of 200 pixels and save or crop out a detail area of your pic and reduce that to 200x200. I have lately been creating a new layer in Corel PP and making a perfect square on it, placing the square over the area I want as a thumbnail, then using the square to make a mask. Then crop the image to that mask. Then reducing the image to 200x200. (dont forget to SAVE AS with a new image name for the thumb so you dont replace the original image. I always use the image name_tn.jpg.) After you have it at 200x200, you may want to sharpen the image a bit and then save it and use a bit of compression to reduce the file size.