Gladly.
Just get the picture you want to show in your post by itself (for example, in deviantART, click "download"), copy that page's URL, paste it in your post, highlight the URL, and click the "Img" button over the text box. That should do it. Like this:
[img]*Image%20URL*[/img]
becomes
If you can't get the picture in its own window, you'll just have to link us to the page you found it on. For that, just copy/paste the URL into the post like before, but hit the "URL" button instead.
[url]*Page URL*[/url]
http://i48.tinypic.com/xbjpkm.jpg