The page you are viewing is "htdocs/index.myt". This page is "wrapped" by an autohandler file, "components/autohandler". The autohandler pulls in "components/header.myc" and "components/footer.myc" to create the finished page.
That's all there is to the simple setup! You can build an entire site just using top level files (index.myt), components (header.myc, footer.myc) and simple inheritance (autohandler). A more automated website might include a "controller" layer. For examples of that, try installing the "myghty_routes" template for a Rails-like approach or the "myghty_modulecomponent" template for a more open-ended approach.