Googlebot (google's spider) finds sites by following links from other sites. the more links to your site they find the the chance of googlebot finding you.
you can check to see if/when googlebot has visited by reviewing your site's logs located on your server. when googlebot visits you will see a reference to 'The little robot that google.com sends out to spider website content googlebot' or 'crawler12.googlebot.com' or something similar.
Seo Packages|Seo Package