Google Webmaster’s Tools – a Quick Tour
If you're not using Webmaster's Tools it's very easy to activate: just go into your Google account and add it to the services you use.
You'll need to fill out your site details and they'll give you a piece of code that you can put into an HTML file and upload to your site. This is so they can verify you're the site owner.
Do that and you're up and running.
Here, then, is a short video that summarises the information and help you'll get from Google Webmaster's Tools: