Online articles usually benefit from including a relevant image or two. A challenge is to make sure that you’re not using a copyrighted image, something that could get you into legal trouble.
You may be able to find good images through Google Images or Bing Images or Yahoo. Just make sure the image you’re wanting to use isn’t copyrighted by Getty or AP or some other lawyered-up organization.
Here are some other image sources, which tend to include copyright-free images:
Public Domain Pictures
NASA Visible Earth
British Library Public Domain
Liam’s Pictures from Old Books
Staff, the site has http://www.iregioes.com.br free and without registration images for low them.