Hi Ashian,
In our theme.skin within the skin, we define the outerwrap to use an html5 <section> element, like this:
<portal:OuterWrapperPanel runat="server"
RenderContentsOnly="false"
CssClass="outerwrap"
RenderId="false"
Element="section"
/>
Then we add module-specific classes via the "Custom CSS Class" module setting, and those classes are applied to the outerwrap. In this case, we added the module as usual, then clicked the "settings" link, found the input labeled "Custom CSS Class", and typed in "main-banner has-banner-icons" as classes specifically for the home page banner module - this allows us to use the simple HTML module but produce many different kinds of styles/layouts with it.
Hope this helps!