for the sig.
if you have a link to an image (you can host image yourself or take it from a website), you'll have to past the link between [img] link here [ /img] (<- no spaces between it)
just thesame way if you want to post a pic in a post.
at least, i think its the way to do it on this forum, on almost every other forum ppl put pics in their sigs this way, so i think its right what i said.