You must put it on photobucket, or tiny pic if it's not already on some kind of website.Then you go to the top of the page to the address bar, and highlight what the address of the site is. Then you right click on it, and select copy. Then go to a topic and cliock on "add a reply." After that, you right click on the part where you type where you want to say.And select paste. So thats how you can post in image, you provide us with the link.
Hope I helped. (Or understood what you were meaning.)