Two weeks older than me then.
To post a picture you upload the picture to flickr or a similar image hosting site. Once its in place, right click on the image and "copy image address" or whatever it says these days. The paste it into this sort of text box, highlight the code and then hit the Img button above. It'll add a bit of code so that the browsers display it as a picture rather than as an address.
Make sure the picture is 72 dpi and not too big. Max of about 800 pixels across, I'd say.
Quote this post to see how it works.