Upload your pic by getting a membership at a place like photobucket.com... it's free. Then when you make a post, go to the image, right click, and copy the location... it'll start with http://
Then type this: [ IMG ]http:// with your copied location here [ /IMG ]
(without the spaces between the [ and the letters, I just have to do that so it'll show up for you)
Hit the preview post and make sure it worked... as easy as pie.