Hi Georgi,
According to what I see on the internet, your camera is an 8-megapixel camera. An 8-megapixel camera will give you a pixel resolution of 3264 x 2448. That means that at 300 dpi which is considered high resolution, the print size will be 10.88" x 8.16". The picture saved in TIFF format which means no compression and gives you the best quality, would be a file size of 22.8 Megabytes. If they are only wanting 200KB then you will have to compress the file using jpeg. If you use a compression factor of 80 the file size will be 199KB, or compression factor of 79 will be a file size of 203KB.
Gerogi, I hope this helps just a little,
Lee711
Puyallup, Washington