Use Dreamweaver's "Attach Style sheet" function to write the code in the above post. Open your html file in Dreamweaver, be sure the "styles" window is available, then, in Design or Split mode, click in the Design mode panel. Clck on the pulldown menu for styles and select "Attach Style Sheet...". The resulting dialog box lets you browse to find the stylesheet you choose.
One more thing..... be sure to UPLOAD the copy of the external stylesheet that you have attached. If you don't, the stylesheet is not seen by the files on the server because it is not there. While you are working on your local files (previewing, etc), your computer uses the local stylesheet as a reference. Stylesheets are not automatically uploaded when a file is "put" on the server. You must put the stylesheet file there yourself.
Hope this helps.
Dave