SEO isn't a script, it's a process. The process of making sure your site is visible to search engines, that they understand what your site is about, and that it is relevant to the search terms people look for.
The best way to start would be to find a mentor. These links should help as well: http://www.seomoz.org/blog/the-web-developers-seo-cheat-sheet http://www.seomoz.org/blog/the-beginners-checklist-for-learning-seo
yeah, in other words, the more visible your site is to the first pages, the more traffic it will get.
You can expand your online presence using SEO coz it will position your website at the 1st page of search engine. There are many script out there that can help you SEO your site such as xrummer.
Just like he said, SEO isn't a script. Site submission isn't a script. You can submit your site to Google and Bing through following URL. http://www.google.com/addurl/ for Google http://www.bing.com/docs/submit.aspx for Bing those are the two major ones. For SEO please read more about it here on DP forums. Find a Mentor , seasoned individual who's been in this space for a while. you can also read more about it here.
The first thing to do is know what SEO is. If you don't know it, you can't use it. And definitely it's not a script. Find business similar to yours and learn from their SEO strategies.