You may add the Google Analytics tracking code to you site either manually or with a plugin. There are many plugins that can help you do this, but I have selected a very simple one, that get the job done simple and sweet.
Adding Google Analytics manually
- Login wordpress admin panel
- Goto Appearance > Editor (theme editor)
- Select the footer.php or index.php
- Find the html tag
- Copy and page the Google Analytics code before the tag.
- Don’t forget to click Update File to save changes.
The only problem with the manual installation is that if you swap your wordpress themes you will loose your Google Analytics tracking. That is why it is better to handle the Google Analytics tracking code within a plugin. The selected plugin is a simple plugin with no-mumbo-jumbo.
Shamefully taken from here for reference