It is very important to reduce the file size of your VSF images. I understand that Facebook reduces the size automatically upon upload. The VSF servers do not, thus you should reduce the size before upload. See the following article on Image File Size odec.ca/CreatingProjects/ImageFileSize.htm
A very good image editing application is Adobe Fireworks. It is rather expensive but has a student price and possibly a 30 day trial.
‘Free’ image editing software that may be useful include: