Here's a free beginner's guide to SEO: http://www.seomoz.org/article/beginners-guide-to-search-engine-optimization SEOmoz are a great site to refer to - a real authority on 21st Century SEO. Enjoy!
There are just many sources of articles please, stick with one in the beginning and just after you have done ALL things advised read other. These things are very time consuming.
Or read the Search Engine Optimization FAQ from SitePoint and Chris Beasley's comprehensive Search Engine Optimization (SEO) Guide, both of which are free (the latter is even available as a PDF file, but you have to register for the forums to get it).