Making a new [[link]] that begins with a / (slash) is the common way to start a subpage. The page to which this link points is considered "subordinate" to its host page, and is titled and linked as [[Parentpage/Subpage]]. It is possible to create a subpage of a subpage (or a sub-subpage). At the top of each subpage or sub-subpage, you can find a backlink (a.k.a. breadcrumb) to the higher levels of the page.
This template is under development and most policies are also still under construction - please fell free to discus them on there talk page or propose major changes at Forum:Suggestions for Improvements it is based on the similiar wikipedia polices in general but were possible simplified and were the projects differ modified to suit.