If posting a pic off another site;
Right-click on image, then left-click on properties
Copy the location line (Firefox) or the address line (IE)
Now, in your posting on BM, click on the 'Img' tab, then paste your image location/address. Do NOT click on the 'Img' tab again (that's the difference to the old site). You should then find that Robert is indeed your father's brother!!!
If you want to post a pic off your own hard drive, you will need to go through a hosting site (I use <a class="postlink" href="http://tinypic.com/" onclick="window.open(this.href);return false;" target="_blank">http://tinypic.com/</a>). Click on 'browse', then find and click on your picture. The file path should appear in the 'file' box. Click 'upload', then when the three boxes appear with text in them, copy the text in the second box down (IMG Code for Forums & Message Boards. Now, paste that text into your post on BM (no need to click on the 'Img' tab; Tinypic has already seen to that) . And that should be it.