Let me warn you all now that the mentioned instructions essentially tell you how to hotlink to an image, ie the image loads from the same web server you got it from. This can be a problem if it's a company's server because they're paying for bandwidth even though nobody's actually looking at their website.

However bad this may seem you're almost certainly fine posting your own images online like that. Flickr, Imageshack, Photobucket, etc all allow hotlinking. (That's what Imageshack and the like are for)

Keep that in mind, some smaller websites may not be able to afford the cost.