I would like to learn about the page hierachie, all you can tell me, please.
Please check out these links and see if this is what you are looking for:
https://confluence.atlassian.com/doc/move-and-reorder-pages-146407727.html
https://confluence.atlassian.com/conf51/changing-the-sequential-order-of-pages-336169197.html
https://confluence.atlassian.com/doc/page-tree-macro-163414255.html