First you have to get the graphic url address of the picture.
It’s the web address of your picture that can be typed in your website search tool and will direct you to the image.  You can find the url of ur pic on tinypic.com, photobucket etc. 
Second, you have type in the url on your post, then add in img tags.  Click/type [img] on either side of the url.  After you post it, you’ll have ur pic and there u go!
If want more further steps/info on it u can find it on Board->Read Only->FAQ’s->How to post images
Hope this helps