Well, it's really straightforward.Create your Google Analytics Account and add the website profile

The add the code to your Blogspot site. First open the Blogger.com management interface
-Layout-Page Elements-
Add a gadget to the site by using one of the links. Custom has it to add the code towards the end (before /body tag which ends the HTML code entries), so we chose the link "add a gadget" for the footer section.A more detailed article can be found on eblogtemplates.com. The only difference is that we have used the the Blogger layout Page Elements to add the code using a gadget. This is far more user-friendly and of course in the spirit of a true CMS application. Before applying our method we checked the web and found confirmation in this German article that this actually works, big thanks to Dirk :-)