If you own your own website where you store images in a file location aka file directory. Simply locate the gif, jpg, or png url for such and post it into your editor. No need for HTML code to do so unless you wish to center or right adjust it. A simple link does the trick thanks to that Markdown support.

It also works I believe here in the comment space. I hope that helps, figured it out the other day :) it's neat too.

Since I own a website it's easy to do. If you need a repository style free site to store images try Webs I been using them for years. If you use it let me know and I'll create a tutorial video guide to help you get your images onto it and locate the files. It's kind of tricky to locate from the Webs dashboard area.