Go to uploads then press browse and pick a picture and go down and pick 640x480 (message boards) and press upload [[thats how you upload] and it shows two boxes and highlight the 2nd box, copy then paste it into a message board/thread.
if you have a picture already uploaded somewhere like photobucket or facebook you can just copy paste the url of the photo. I use my FB pictures- just right click the pic, click on properties and copy the url. Click on IMG (right above the smilies and insert the URL between the ] and the[ or you can just type URL [IMG]