Assuming you do, then all you have to do is upload your pic (JPEG or GIF) and a link to it will appear at the bottom of your post.

If you want to get sexy, then you can display an attached image in your message using the standard HTML img tag:

<img src="url of the attachment">

If you happen to resize your image prior to uploading so it's 640px or 320px wide, then using the following HTML instead will put a nice border around and centre it, optionally with a caption in smaller text.

For 640 pixel wide images:

<div class="image-centered-640"><img src="url of the attachment">optional caption</div>

For 320 pixel wide images:

<div class="image-centered-320"><img src="url of the attachment">optional caption</div>

Yes, I know you've got to type the HTML and it's a pain - but at least you can cut and paste from these examples.

And the "url of the attachment" can be "url of the remotely hosted image" if you want - no need to upload the image here if it's already on some other website[1].

--
simon

[1] But don't start linking directly to images you don't own the copyright of, naturally.