You don't really have to have the access to the html code of Blogger.com.
You can do the following:
1. Go to Settings tab in Analytics tool. Then navigate to Tracking info -> Tracking Code.
2. Copy the Tracking code to notepad.
3. Go to blog settings in Blogger.com.
4. Click on Template tab on the navigation bar on the left.
5. Click Edit Html for the the template which is live on Blog.
6. Paste the Google Analytics Tracking Code from notepad to the top html code right before closing head or body tag.
7. Save the template.
That's it. Next day the tool will give you the traffic information to your blog.