Do you have any photo editing software?? You might have got something with your camera. Check those out. Then find a menu that talks about resizing. Perhaps right now the picture is at some big Resolution like 2048 X 1024. OK just scale that down to something like 400X 150 or so. then save and see if it is small enough. Won' t look as good but it will help you post. I had to go through the same drill.

Good luck.