go to a hosting site - like
www.photobucket.com or
www.imageshack.us and host your picture.. to do that click browse and then find the image on your computer and click that - then click upload or host.
a bunch of url's will probably come up and just find the one that says direct link to image. i know on imageshack if you scroll to the bottem of the page it says it.
anyways copy that url and paste it here but put
after the url and that'll make it show up in your post
if you dont understand still just lemme know