Just find the image's location and type in this :
<img src = "http://somewebsite/somefile/image.jpg">
You find the image's address "http://somewebsite/somefile/image.jpg" by right-clicking on the image, selecting "properties" and copying the source.
Of course, the image actually has to be up on a web site in the first place. An image that is just on your computer won't work.