where should i add this code?

I got the zopim code

<!-- Start of Zopim Live Chat Script -->
<script type="text/javascript">
document.write(unescape("%3Cscript src='" + document.location.protocol + "//zopim.com/?LAcC2qg4upZl3l7mfyaRgwqQ8ax7dPCR' charset='utf-8' type='text/javascript'%3E%3C/script%3E"));
</script>
<!-- End of Zopim Live Chat Script -->

But i am not sure where should i place the code so it will appear everywhere. If i put it with any of my side boxes the page stop loading. If i put it under define main page it only shows up on the main page and not others.

I tried style sheet at the bottom, i was told something about before the template close but i haven o clue where is that :(.

Generally speaking, you don't add javascript to the code files, but follow a process of creating a jscript file, storing it in the jscript folder of your template, then creating a reference to that file in the relevant page(s) header file(s) (in the MODULES / PAGES folders.

The method is described in many other posts... look for "javascript".