There are a gazillion 3rd party hosting sites. we recommend http://www.TinyPic.com or http://www.Photobucket.com (select the 800x600 option for your picture for best forum results).
Once you have uploaded your image to a 3rd party site, find the link to the picture. usually it says something like 'direct link to image' box, or something similar to that. Copy that link. If you want to see if the link works before posting to the forum, just paste the link into your browser in the url address field and see if the picture comes up in your browser. If it does, you have a good link.
Once you have the good link in your clipboard, in the message you create, place your cursor in the message where you want the image to go, click the Img button right above the message text box, and paste the link right where the cursor is between the new little code snippets that it dropped in for you. And Wallah, your done.
