Its very broad question and its very difficult to answer but let me try - SEO is all about getting your site achieving high ranks, preferably first rank in Search engines,preferably Google. Search engines consider various parameters for ranking so in SEO what people do is, they follow set of practices to score well for those parameters. For example, if you Keep a title with your keywords as well as a url with keywords than tehre are good chances u will score well in search engines provided there is Not much competition. This is just an example of on page SE optimization. You can check my SEO tips section if you want to know more SEO practices, link and traffic building.
Yes, I would agree! SEO (Search Engine Optimization )basically, it is getting your page into it's higher search engine ranking. In order for you to do this, you need to drive more traffic into your site and you can either do this by emailing, do links with other sites etc., but the most important thing to attract visitors to go and jump in to your site is that you must have of course a good content to your site.