what i always do to lower the space taken up by pics is:
1. open up the pic in MS Paint program (Right click on the image, go down to "open with" then click paint")
2. when in paint program, click "image" then go down to "sketch/skew"
3. set the horizontal width to 40% or so
4. then set the verticle hight to the same percentage as you set the width (in this case, 40% or so)
5.click "ok" in the sketch/skew window
6. then click "file" then go down to "save as" then save where you want it
7. to be safe, save it as a jpeg format image.
when you upload pics again, if its under 100kb it should work
i hope my steps helped, i tried making it as clear as possible