So many grumpy faces today!!!!

Take a pic...or steal one. Your choice. Upload it to an imagehost such as http://imgur.com. Get the link for said upload (usually by right clicking on the image and selecting save url. Type [ img], paste the link, then right after the link type [/img] (no spaces). You will end up with something like this;

[ img ] your.image.link.here[/img ] - no spaces

Be mindful. What goes out on the internets cannot be deleted from the internets.