John,

To edit the html for the skin you'll need to make changes to the .ascx skin file which can be found in the skins folder. The easiest way to find the directory for this is to look in the source code of one of the pages using the skin, and find the location of the skins.css file. It should be something like: Portals/_default/Skins/skin_name/

If you want to make changes to the CSS, you can edit the skin.css found in the same directory, or add it to the stylesheet editor which is found in admin > Site Settings, at the bottom of the page

I've created a couple of videos that could help as well, and they can be found here: http://www.youtube.com/psdtodnn

If you're looking to do something specific, can you include the details of this in your next post?

Hope this helps.

Rick.