"Responsive Web Design" means building a page that can be viewed on any size screen, as opposed to building a separate page for mobile devices and tablets. RWD works by setting rules as to how a page should look at various screen widths. These rules are implemented as 'media queries'.
If you would like to learn how to do this, then there's a tutorial on Flash By Night for you! Just follow this link:
http://flashbynight.com/tutes/responsivedesign/
If you're an HTML beginner, no probs, you should be able to follow along. The tutorial will take you around an hour or so.
