right. URL stands for "uniform resource locator". When you upload the picture to the web, It gets a URL assigned to it, that's it's "address" on the web. But a lot of these sites that host pictures also give the option to put tags at the beginning and ending of the address. For example the tags that allow the picture to be shown on a bulletin board page rather than just a link. If you try to put in a URL with those tags at the beginning and end it won't work.
The easiest way to get the URL from an image- minus the tags and all is to right click on it then hit "properties".
I could not get it to upload from my gallery, though with a 200x200. I might have screwed something up there.
Also could not get it to upload directly from my computer.