Okay let's get this settled once and for all lol.
Use an image-hosting site if the picture's on your computer such as:
Image Socket
Photo Bucket
Or any other hosting site.
Upload it and they will provide you with the location of the image, sometimes you can just copy and paste it, if it has the [img]tags%20already%20on%20it,%20if%20not,%20just%20copy%20and%20paste%20the%20URL%20location,%20surrounded%20by%20[img][/img]
If the picture is ALREADY on the web, just use the above method. Cheers.