How to deal with google share button?

Question

Google

using code

<a href="https://plus.google.com/share?url={URL}" onclick="javascript:window.open(this.href,
  '', 'menubar=no,toolbar=no,resizable=yes,scrollbars=yes,height=600,width=600');return false;">google +</a>

Instead of URL, what should be specified? Or what script to add so that the page on which the button is poked is rummaged.
I will be grateful.