OH C'MON COWBELL!!!! There's a faq on this! ~sigh~ ALRIGHT! Quick and dirty version.
It can't come from your computer. The pic has to be online and can't exceed a certain file size or pixel size. I'm not sure on the limits of pixel size, but throw an image into the line to see if it's within limits of posting. A prompt will tell you if it's too tall or too wide.
Hope it helps. AND TELL YOUR FRIENDS FOR PETE'S SAKE!!!! SPREAD THE WORD TO ALL FOUR CORNERS OF THE EARTH SO EVERYONE KNOWS WHAT TO DO WHEN THEY GET HERE!
~sigh~
I'm Ghost!
Ghost Dragon