The IMG tag requires a URL to a picture hosted on some website. If this site still had a personal gallery and direct URL access to the file itself, you could use that, but the gallery has been shut down so you need your own source.
If your ISP provides you with a personal webspace, you could upload the picture(s) there, and reference them through the proper URL in the IMG tag. The pictures you host at your personal webspace do not have to be referenced in the default webpage or advertised in any way.
You can attach pictures, as you can with many other file types, without having to host it elsewhere, but they wouldn't be in-line in the post.