As Ben said, you need to start over. People interact with their mobile devices very differently from desktops.
- There's no mouse,
- the screen is smaller,
- navigation & forms must be fat-finger friendly,
- mobile data plans limit how much bandwidth the mobile user can absorb.
All of these things must be considered when planning a Responsive Web site. I like to build my Mobile layout first followed by Tablet and finally Desktop. I use CSS Media queries to target the various device widths.
Responsive Web Design
http://coding.smashingmagazine.com/2011/01/12/guidelines-for-responsive-web-design/
Introduction to CSS Media Queries
http://www.adobe.com/devnet/dreamweaver/articles/introducing-media-queries.html
Nancy O.