It has apparently been programmed by a writer. You want to write the Great American Novel (your Longform folder, proj1).
Then you start out with a draft, which contains scenes.
Drafts get edited (but are usually kept for a while), thus you can create new drafts from older ones.
Everything is kept together by an Index.md file in the Longform folder, which shouldn’t be manually modified.
Overall structure is like so:

So the first step is: Click on Drafts and fill in the name for “New Draft”.