Hello @BatMan,
Use collections to achieve a folder structure. See the recent post here about a similar feature request but that can actually be done: UX Improvement: Persistent Tree / List View to Avoid Context Switching (Three-Pane Layout) - #11 by aleclerc
Also, note that collections embeded in a page will not respect manual sort order, or any order. But if a collection is pinned, this will work. Embedded Collection sorting does not respect order in the left pane (Tree Layout)
You can add collections to collections, so this creates the illusion of folders. Yet, make sure put the pages (or stuff) you want in the collection where you want it.
Hope this helps and kind regards!