How to add classes to the HTML module

I added an HTML module to my DotNetNuke page. When I go into the editor for the module, there is a drop down "Apply CSS Class" that is empty with the exception of "Clear Class". How do I create classes that I 开发者_Python百科can use for the HTML module? Where should any related CSS files reside in the file system?

Found the answer, the latest versions of DNN are using a new provider for the HTML Module, Telerik's RadEditor. DNN details on configuring the "Apply CSS Class" drop down can be found here: http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/108/threadid/364908/scope/posts/Default.aspx