Thanks for inviting me to answer the question. I'm on the same page as you but a little bit further, I have done front-end development but diving into the back end is almost completely different.
Took me quite a while to get my head around learning the node js and how it plays in a big part of development. I agree with the chap below about the HTTP server, build it a few times in a few folders and you'll soon understand how a project works.
I've been on Pluralsight and there's a good Introductory Node JS course on there which deep dives more into what node js is.
Node is very much, sticking your hand in a cookie jar and eating all the cookies at once, it will take you time, and alot of research and learning the differences between the modules, the features, what NPM, SNAP, Yarn, Web Pack, ... So many!
For me it's all about knowing the structure of the folder, and the architecture understanding what node is as well as how to use it.
One thing someone asked me the other day about this while using node and npm, he was trying to get the index.html page to work and asked me, well where do you put the index.html file. I had to tell him, well.. When I find a place I'll let you know but from what I've seen you write and its then possibly complied into xyz language bit like pug/template with express.
I have also found helpful to listen to latest podcasts about the latest trends on the market, node is a big competitor for python at the moment and it will be interesting where they both go on the market.
Good Luck!