Standard Page Elements
Websites tend to have very common structure elements. LigaType defines standard ones. You don't have to use them, but they're there if you want to use them, and you can of course use your own different ones if you wish.
Standard page elements appear hierarchically. This means you can have a sidebar specific to one folder in your site, but all the other sidebars use your main site-level one. You can edit these items just like any other item. There's nothing special about these page elements except that their names appear in all of the standard skins (which you can change anyway).
header.html - the header area of a page
footer.html - the footer area
sidebar.html - the sidebar, right or left
navbar.html - a navigation area
You can edit any of these items directly from the file manager for your site.