Good articles on how to use keywords within web site content and code:

http://www.shayhowe.com/seo/keyword-dos-and-donts/

http://ezinearticles.com/?Seo-Tips—Keywords&id=431617

http://www.seotier.com/8/seo-meta-tags-guide/

http://www.searchenginejournal.com/the-importance-of-keywords-meta-tag-in-seo/6014/