on my sansa fuze i uploaded some jpeg pictures on to it and they worked fine, but when i tried to upload some jpeg pictures i got off of my camera, it just says unsupported media format. the thing is, is all the pictures are jpegs, but only the ones off the internet work
To add picture files you need to use Sansa Media Converter, or possibly video4fuze. These will resize the files and make them into something the fuze can use.
You can use any image editing software to make smaller copies of your jpg photos. I believe the largest size the Fuze will support is 1024x768, however you can save space by using a smaller size. Use a size at least 220x176 though, which is the screen resolution for the Fuze.