If you have the picture hosted somewhere (i.e. Yahoo Photos, Webshot, your own website) just do this...
- Click on the button in the "add yabbc tags" section that looks like a picture. It will say "insert image" when you place your cursor over it.
- [img]http://www.domain.com/picture.jpg[ /img] is how you want to enter the URL of where your picture is hosted.
If that doesn't work you can upload it by adding it to the posting as an attachment.
Any further questions shoot me a PM. Hope that helps.