Well you can't use that banner in your signature because the bottom half of the girl has nudity in it. It would need to be covered with a bikini or something.

Also it shouldn't be too big as those can break the table and cause the page you post in to look horrible. And the big banners are really just annoying imo.

As far as how to get a banner to appear in your signature, I'll have to go research that myself as I don't do HTML very often and I don't use a banner in my signature:)