You're close.. the image URL means that you need an internet address to the picture.. it doesn't have to be on the internet, but it has to be online somewhere. There are a lot of free image hosting services out there. And check with your ISP almost all ISP's offer a free place to put a webpage or photos online.
If that fails you can always ask someone to put it online for you and just email the picture to them..
Good luck,
-=Andrew=-