how to use custom theme css file

how to use custom theme css file


I have used the default Flora theme with the jQuery UI widgets
successfully. I then downloaded a custom theme from the ThemeRoller
site (http://ui.jquery.com/themeroller#themeGallery). After I included
the "ui.all.css" file, how do I use the css classes in the custom
theme?
For example, I had
<div id="example" class="flora" title="This is my title">I'm in a
dialog!</div>
Now I changed it to
<div id="example" class="ui-dialog" title="This is my title">I'm in a
dialog!</div>
and the css does not work. What do i need to do to utilize the new css
settings from the customized theme roller files?
thanks,
niner