You can do it...I'm a grandmother too. The picture of your ducklings is at 800X600 on your My Page. At photobucket select the picture, at the top of the picture click "edit".
The picture will come up again, at the top click "resize". If you check out my My Page the top photo has been resized to 640x480 message board size. The rest of the photos have been resized to 320x240 website, e-mail size. Warning though, once you resize them smaller at photobucket you can not resize them up. You have to upload them from your computer again.