set second level as header title

I’m not exactly sure what you are asking here. For the first one, you just set a “Posts Page” under the “Front page displays” option in Settings > Reading. For the second, pages in WordPress don’t have a custom root page, you have to create a “custom root page” yourself and have pages children of it (or children of its children). Breadcrumb NavXT will pick up on both of these organizations automatically.