1. You need also the start tag<noscript> if you want the </noscript> end tag to have a meaning. Do you know what <noscript></noscript> does?
2. You must find a way to refer that image element. If you have no id, no class, no nothing, you must find something which is characteristic only to that tag. Could be the position/order in the DOM tree, but for that you should told us the position, or to count it by your self.