Google Analytics currently is the most powerful tools to see your website convertion. It can be use for test your web page, promotion, convertion rate, traffic source, visitor behaviour, etc.
The other good thing is, it’s FREE! Google create this tool for you to help you create more money. Make sure every website that you own using Google Analytics.
Follow this step-by-step tutorial on how to create and install your analytics code:
Go to http://www.google.com/analytics