There are several places on the forum explaing how to do it...
If you look below this box you will see a "manage attachments" button. Click on it, upload a picture and you are good to go...you can always preview first to see if you got it. There is a testing forum here too, so you can test it. You can also add a url for a picture that is hosted somewhere else by clicking on the little yellow mountain right above this box and then inserting it.....try it a few times and it will be easy...good luck
edited to say that you have to be in the middle of a post to see what I was just explaining
http://www.net54baseball.com/faq.php...b3_attachments