First, go to
ImageShack® - Image Hosting, Browse for image you wish to upload and wait when it uploads it. When new site appears, scroll down and look for '' Link to direct image ''. Copy this link, and in here click the '' Insert Image '' on the quick or full reply window. Paste the link there, push ok and post reply. You're done.
Alternatively you can write the image tags yourself, such as [IMG] * insert the link here *[/IMG], without the space between the tags and the image.