generally I think we do things as bitmaps but need to down size to jpeg format to upload. some forums have limited picture space so you have to keep reducing the size as a bmp file then save as a jpeg file until it fits either size width x height or kb limit.
dont htink you can edit a jpeg so have to save as bmp first.
If you are running XP and Microsoft Office, if you go to Programs/Microsoft Office/Office Tools/Picture Manager. Once you have launched it it should default to open most picture files and you can also resize etc very easily from there.