That tutorial is a couple of years old, so I'm sure that some of the details are just a bit out of date. So, let's take a look at the skin to see what is there ...
Looking at the Horizontal Menu - Full Width skin, I see this ...
< TD width="100%" vAlign="middle" align="left" nowrap >
< dnn:NAV runat="server"
id="dnnNAV"
ProviderName="DNNMenuNavigationProvider"
CSSControl="main_dnnmenu_bar"
CSSContainerRoot="main_dnnmenu_container"
CSSNode="main_dnnmenu_item"
CSSNodeRoot="main_dnnmenu_rootitem"
CSSIcon="main_dnnmenu_icon"
CSSContainerSub="main_dnnmenu_submenu"
CSSBreak="main_dnnmenu_break"
CSSNodeHover="main_dnnmenu_itemhover"
NodeLeftHTMLBreadCrumbRoot="
!["*"]()
BORDER="0"
src="breadcrumb.gif"/ >"
/ >
< /TD>
Now, without knowing too much, it appears that most of the "CSS" named items refer to CSS classes that style different parts of the menu.
Coupling that with
Troubleshooting DotNetNuke Skins, the tutorial that shows you how to user the Web Developer's Toolbar, you can easily create a page with the Blue skin and track down the various styles. For example, main_dnnmenu_bar has a background color that will color the menu bar. Others style the text, etc.
I'm still looking for some documentation ...