t4gal on "How to add certain version of Jquery"

I'm using a bit of script on my page that relies on the following Jquery:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>

How do I properly add this to Wordpress? From what I've read, simply inserting that code into header.php is not the safest way to go, is this correct? How do I go about doing this properly? I'm very new to this so the more detailed the instructions the better, as the information I've found on google so far doesn't make much sense to me.

I'm using a child theme based off of Twenty Thirteen.

Thanks in advance.