I'm not the greatest on giving technological advice, but you can resize them yourself.
Upload them to your computer, and then, using a photo program (Picasa or Irfanview, for example), you can "resize" them yourself, reducing the resolution. Be sure to save the new photo under a different file name, or you will overwrite the original.
I'm sure someone else will chime in on how EXACTLY to do that..... it takes me a few tries to remember how to do that!