You don't really need a script. You can use a template component and write html in that template that looks like this
<a href="LINK_URL"><img src="IMG_URL"/></a>
You can see a slightly more complicated version of this in the Skuid app. In your pages list open the page "SkuidCoreMaster" and you'll see the skuid logo in the header. Its using the template approach shown above to link to the skuid central help site. You can't change this page - but you can learn from it....
We have on the roadmap the addition of "on click actions" to the image component. But they are not there yet.