Free guide will get you started...
http://www.seofaststart.com/ This guide that Lynn recommends is the best place to start. (I kiddingly call it the bible of SEO. It's not hard to follow.)
When you have one keyword, it usually is too broad for getting the targeted reader you want to come to your website. Selecting the keywords and phrases that will attract those readers you want to come to your site, read your stuff, and buy what you offer, is what you will learn here as you ask the questions while learning and practicing what you learn.
Lynn will often supply links here in the forum and on the webinars that directly answer your questions so don't hesitate to ask.
Hope that helps, Chris.
Best for now,
Mary