Where to add html content for new sidebar

Just getting started here ... I want to add an additional right sidebar panel with a countdown to date timer (days-hrs-mins to EXPO 2014); I don't want to replace the existing sidebar, just put this content at the top of the right sidebar column. I clicked create new sidebar, but I'm not seeing where to put my html content. Already added the javascript call to the header and the css to the theme application.css file. Now I need to place the html. How? Please!