Apologies for not knowing the right terminology. I have structured my novel-in-progress in such a way that all my files are under “Chapter.” How do I create another Chapter folder? Can I move my files to another level (such as from A to a in outline form)? Pressing the green + only creates another file under Chapter. In Word, all I had to do was press Tab. Help!
To create a new folder, click the down arrow next to the green + sign and choose New Folder.
To move items in the Binder around, drag and drop them, or select an item and move it using Ctrl + arrow keys.
For more details on Binder item creation and navigation, see the Interactive Tutorial (Help > Interactive Tutorial), the page Draft > The Basics > Get Oriented > Main Interface > The Binder.
The documentation in §6.3.1, Adding New Items, of the user manual PDF may be of some help here. In particular the subheading, Figuring Out Where Things Will Go, discusses the most efficient ways to create new items. For example, to create a new folder at the same level as the current one you’ve been working on, instead of selecting the very last section of text in that folder, try selecting the folder itself.
That said, you can always move things around (like “Tab” would in Word, if I understand correctly). For small changes like that, the shortcuts in Edit ▸ Move are easy to use. For larger changes you can always just drag and drop to move elements around in the outline. All of the different techniques are documented in §6.3.4.