miriamfalk on "ok to put this javascript into my index.php page?"

I am an affiliate marketer. My website is welldressedflapper.com. A company I want to work with has requested that I prove my ownership of the site by temporarily adding the following JavaScript to my index.php file:

<script type="text/javascript" src="http://www.avantlink.com/affiliate_app_confirm.php?mode=js&authResponse=c0e403b9c022a0560d012207989d88d810197428"></script>

I have located index.php in the editor but I'm new at this and very nervous. Is it ok if I insert this code into my index.php file? Is there a particular place where it should go?