Starting a personal challenge - hotel-application how to?

Hello guys,
I am quite new to programming, currently i have a friend whose mother is owning a small hotel on an island, she is handling everything with papers right now, my friend asked me if i could help doing some app to help handle the hotel. I accepted, as a challenge to progress in my dev career.
Well now, i m wondering where to start, I asked him everything she is doing in day to day job , read bookings, make a booking, see the bookings , see the rooms available…

I was thinking of starting the back end, with node.js, but what are the steps actually before i actually do i start the front end part ? I would need some advices there… ! :slight_smile: