I'm an idiot, I don't know how to do a screen shot, but here's my wallpaper. I change it from time to time with pictures I take while fly fishing. This is the "Upper Falls" on the Ammonoosuc River in New Hampshire.
I'll bet that cake didn't look like this a few minutes after the picture snapped.
Usually you just hit the prt scr button on the keyboard and it copies whatever is on the screen to the clipboard. Then you use photoshop (or similar) to load it up and save it to the correct format, jpg. You can then upload it to something like photobucket.com and copy the url here.
I use Paint and Imageshack.us. Paint comes free with windows, and imageshack.us doesn't require you to sign up. I'm not sure if Photobucket has an instant upload thing like imageshack since I haven't used it in 2 years.
I've used it for about a year and a half. They must've impoved it since you used it. You do have to sign up but it's free. The uploads are pretty quick and can be used right away.
I use Paint Shop Pro X, but Paint ain't bad for this purpose. I had to do a "copy to new image" command and that created the clipboard capture of the desk to a new image. then I could shrink it a bit and save it. I'm not sure how it's done in Paint.
I just paste it and save it as an .jpeg image. If I wanted to resize it, I just go into the "Image" menu and choose "Strech/Skew". I can then change it using %'s.
A few years ago I had no idea how to do it. But I had an app that would record movies of all desktop activity. So I'd do a short movie, then I'd run it on a video app that allowed me to take snapshots. Way too many steps!