I was confussled a while back about it too. One thing i tried was to shrink my screen and take a shot, but the centering was really bad. THis is that way to do it:
1. Go to photobucket and register.
2. take screenshot of item and stats if u want on gw.
3. upload the shots on to your album on photobucket.
4. click on the photo and click on the "edite picture" option above.
5. crop the area you want and it will resize itself.
6.(Optional) resize the shot(s) to whatever size u want(that will fit)
7. load the pic onto ur auction.

I hope this helps, if not tell me and ill try to answer it better.
