If you use feedburner and you want to turn on site stats for your blog then you can use the following script tag in your layout.liquid file. Be sure to put it in the head section. The layout.liquid file is located in the design tab of the admin.

Be sure to replace FEEDBURNER_ADDRESS with your adress from feedburner & BLOG_URL with your blogs root url without a trailing slash

For example my info is:
FEEDBURNER_ADDRESS = CommonThread
BLOG_URL = http://blog.commonthread.com

<script src="http://feeds.feedburner.com/~s/FEEDBURNER_ADDRESS?i=BLOG_URL{% if article %}{{ article.url }}{% endif %}" type="text/javascript" charset="utf-8"></script>

That is only for people with TotalStats Pro. If you are using StandardStats then you will use:

<script src="http://feeds.feedburner.com/~s/FEEDBURNER_ADDRESS" type="text/javascript" charset="utf-8"></script>