This is directly from google. Here is the link.
http://www.google.com/webmasters/1.html
"2. Submitting a site
We add thousands of new sites to our index each time we crawl the web, but you may submit your URL as well. Submission isn't necessary and does not guarantee inclusion in our index. Given the large number of sites submitting URLs, it's likely that your pages will be found in an automatic crawl before they make it into our index through the URL submission form. We DO NOT add all submitted URLs to our index and cannot predict when or if they will appear.
Please visit our Add URL page to input your URLs. You can submit your site as often as you like, but multiple submissions won't improve the likelihood of your site being added or accelerate the process. We don't penalize sites for "over-submitting." If you choose to submit your site, only the top-level domain is necessary, as the spiders can follow your internal links to the rest of the pages.
You may also use the Google Sitemaps (Beta) program to create and submit a detailed sitemap of your pages. We're testing this as a complement to our current crawl and encourage webmasters to participate. Google Sitemaps makes it easier for webmasters to provide information about their sites, and to update us when pages are added or changed.
The best way to ensure that Google finds your site is to have pages on other relevant sites to link to yours. Google's robots jump from page to page on the web via hyperlinks, so the more sites that link to your pages, the more likely it is that we'll find them quickly."